Adela Holzer might have sprung from a Harold Robbins novel. There simply is no other way to explain her. She astounds even the prosecutors in the New York attorney general's office, who have seen it all. "She's incredible," one of them said recently.

Judge Richard Denzer came to the same conclusion in New Yok State Supreme Court yesterday and sent her to prison for two to six years. The decision was immediately appealed by her flamboyant attorney, Roy Cohn.

Unless Cohn can produce more magic on appeal than he has thus far, her slide from an opulent upper East Side townhouse to state prison now appears complete. But at least her housing problems will be over.

Until last week, she had been living alone in a room on the third floor of her old townhouse, which she lost at a bankruptcy sale in March. Booted out by the new owners, she claims to have been sleeping in the business office of one of her sons since then.

While still at her old house, she had prowled around the deserted place alone after the sale, peering at the rubble in the backyard and examining the bare walls while she waited for sentencing.

But the house had lost its elegance, and she her magic.

"I have to redo my life," she concluded in a moment of great understatement.

Adela Holzer inevitably invites comparison to Jay Gatsby. Both went far and came down hard. Neither tasted success for very long. Both had dark sides to their lives, which they managed to hide from a world they sought to impress until their demises.

The only difference is that Jay Gatsby never had to sit through the public dissections with the shady characters who fixed the 1919 World Series.

When Gatsby was in his prime, he entertained lavishly and desperately for acceptance into the top echelons of West Egg society. At her peak, with a string of Broadway hits behind her, such as "Hair," "Sleuth," and "The Ritz," Adela Holzer basked in the approval of le tout monde in New York and solidified its affection with her frequent dinner parties.

She carried a magic name as a Broadway producer and entrepreneur in the decade spanning 1967 to 1977; she was everyone's darling in those days-"the angel of Broadway," as one New York paper put it.

Today, while Cohn calls her "an extremely imaginative woman," Mark Tepper, the assistant New York attorney general who successfully prosecuted her for fraud last winter, describes her as "a mistress of manipulation," "one of the cleverest and most successful white-collar criminals in the history of this state."

From the bench, Denzer described Holzer as being motivated by "plain and simple greed." Where Holzer claims to be the victim of a travesty of justice, Denzer said, "There was no doubt that her entire enterprise was fraudulent from beginning to end." Creditors are still seeking almost $13 million in claims from her.

"She's a big fake, a tireless self promoter," added one individual well acquainted with the New York theater world On Her Own

Adela Holzer remained officially outraged right up to the end. "I can't believe this injustice could happen in this country, she said moments before her sentencing yesterday. "In dictatorships, yes, but not here. I'd have never come here if I'd known this could happen."

While she came from a wealthy Madrid family, she abandoned financial security and a foundering marriage to a man twice her age at 20 for a shot at New York. She arrived pregnant and broke in 1954 and proceeded to carve out a remarkable, if mercuiral, career on her own terms.

Still, her fall has been monumental, and the now total absence of money, along with the humiliation she has sustained from her six-weeks trial, her conviction, and her sentencing, tests all of her reslve. Consider this.

Barring a successful appeal on an error of law in her trial, an event which is unlikely, she will spend a minimum of two years in jail for seven counts of grand larceny. These stem from indictments issued in 1977 charging her with 248 counts of defrauding investors of $2.3 million. To save time, Denzer dismissed all but seven representative counts last winter, and a jury convicted her on all seven. 'I'm Not a Crook'

She lured money from investors through phony international business schemes. Her business dealings were as exotic as they were complicated, and involved auto dealerships in Indonesia, land deals in Spain, and trading companies in South America.

Then, too, she remains firmly in the grip of a federal bankruptcy court which recently sanctioned the sale of her townhouse at public auction for $400,000. There are literally hundreds of people looking to her for their money. In all likelihood, they will never see it.

Finally, she is in the midst of an ugly divorce from her third husband.

She claims to have applied without luck to the Waldorf Astoria for convention work and to have returned recently from a local welfare office empty-handed. One of her two sons had to drop out of law school last year because of money problems, she says, and her other may face a similar situation at college next fall. "No one wants me now," she muses.

But Adela Holzer has a bit of Richard Nixon in her along with Jay Gatsby and Molly Brown; she comes out swinging when she is cornered, and she displays a convincing belief in her own innocence, regardless of the facts.

"I'm not a crook," she said recently. "My only mistake was neglecting my business interests overseas. If I were in civil court for negligence, okay, but this trial was a monstrosity.

"They wouldn't let me leave the country to get the evidence I needed to prove my innocence," she continued. "I tried to locate where the money went, but it's impossible to do it from here."

According to one of her lawyers, John Lang, she could have pleaded guilty to one felony count and probably have avoided jail and the entire trial. "She would have walked, I think," he said. "But she said "absolutely not.'"

Holzer was born Adela La Fora 45 years ago in Madrid, and grew up in a family which derived its considerable wealth from a string of hydroelectric plants across Spain. Although well educated, she faced sorely limited career opportunities in the decidedly male-chauvinist Spanish society, she claimed. Her first marriage was a disaster, also, and she decided to make the leap across the Atlantic in 1954 to try life on her own.

With precious few funds, she sailed first class on the Queen Elizabeth and promptly checked into the Plaza when she arrived in New York. The job prospects were not great, however, and she soon lowered her sights. For two years, she worked at the United Nations as an interpreter, and then moved on to a Manhattan advertising agency for a year, where she absorbed marketing technique and wrote copy.

Less than a year after she arrived in this country, she was indicted for grand larceny and forgery, but the charges were dismissed. She had been accused of forging a Spanish notary stamp on a note worth $3,000.

It was while teaching Spanish at Columbia University for nine years that her own marketing skills surfaced. Exploiting the long academic vacations from her connections from her days at the United Nations, she ventured into business deals in South America. Her acumen proved to be sharp, and her breadwinning became a lot easier.

In the meantime, a second marriage had come and gone. A physicist, again more than twice her age, died in an automobile accident after four years with her.

By the mid '60s, Adela Holzer was alone again, but financially secure. She was a striking, vibrant business woman with a reputation for the dramatic, and she was looking for more glamorous ways to increase her profits.

The answer, she decided, lay in the theater, where adventurous spirits can make a killing or lose their shirts with brio .

Her first foray into the theater world was, unquestionably, a success. But like so many other parts of the puzzle, it is clouded with controversy.

Ask anyone who knows Adela Holzer, and they will tell you that she struck it rich in 1967 with the musical "Hair." The story goes that she made $2 million on an investment of $57,000 and that the profit greased her entrance to Broadway on a wider scale.

While claiming that the $2 million figure is "slightly high," Holzer stands by that figure today.

Yet Tepper claims that she made a good deal less-about $117,000 in all. "I had heard $125,000," added one prominent theater figure.

Whatever the case, her initial success in chutzpah launched her career as a Broadway investor, with mixed results. There were "Hair," "The Ritz," "Sleuth," "Sherlock Holmes" and "Monsters," all of which made varying amounts of money.

But then, too there were "All Over Town," "Bad Habits," "Where Has Tommy Flowers Gone," "Voices," "Brain Child" and "Truck Load"-all of which lost money. "Dude" cost her about $250,000 of her own money in 1972.

"Dude" was one of the biggest musical failures of all time," said Harvey Sabinson, director of special projects for the League of New York Theaters and Producers.

According to the New York attorney general's office, she lost some $3.2 million on 10 plays when she was the toast of the town.

"Her career on Broadway was not successful at all," said Mickey Alpert, her former, theatrical press agent. "The record stands for itself."

But, again, it was the image that was important, and hers was flowering. Now married to shipping executive Peter Holzer, she was associated with one show after another. She was willing to take risks and to lose large amounts of money.

"She came to the theater with a lot of money to spend and that made her attractive," observed Robert Whitehead, a theatrical producer and partner of Roger Stevens, now the director of the Kennedy Center. "She had a lot of determination withou any knowledge."

"I remember watching her on a talk show a few years ago," said Sabinson. "She said that she was going to make the theater world forget about David Merrick."

It was during these days in the mid-70's that she entertained lavishly at her townhouse on East 72nd Street. She dressed well and oozed cosmopolitan sophistication. The only question that loomed in the minds of some was where the money was coming from to take financial beatings like the one she sustained in "Dude."

"There were years when I had an income of $300,000 from any business interests," she explained. "It was all legitimate. The truth was that I never had any headaches from the IRS."

While some didn't buy her penchant for flair and self-promotion, no one in the New York theater world appears to have anything bad to say about her financial dealings there.

"In all of her dealings with us, she performed every one of her obligations perfectly," observed Gerald Shoenfeld, president of the Shubert Organization, which owns 17 of the 37 theaters in the Broadway area. "She was faultless in all of her transactions. I have never heard her actions questioned at all, and people have a tendency to know doesn't perform in the theater. It's a small world."

"Naturally, the theater people got paid, so they thought highly of her," said Tepper. "She made sure that they were taken care of first."

Tepper charged that Holzer ran a classic "Ponzi scheme," named after a man who bilked about $20 million from investors in Boston in the 1920s.

"She would take the money from the new investors and pay the old ones," he explained. "It is like a chain letter. Someone is bound to get burned in the end."

According to Tepper, Holzer took in $8 million in 1975 alone from investors, $1 million of which went into theatricals. She claimed to have the sole Toyota dealership in Indonesia, and she was putting together lucrative real estate deals in Spain. The investors came to her.

"I never solicited. They always came to me," she explained."They begged me."

"But then she took in only $3 million in 1976, and she had a tremendous cash flow problem on her hands," Tepper continued. "She claimed to have $10 million in a Chase Manhattan branch in Jakarta in 1976. But according to Chase, she had $456.56"

The roof caved in on Adela Holzer in the summer of 1977, when she was indicted for bilking investors of over $800,000. She was indicted again that October. This time, the ante was raised, and the New York attorney general's office charged her with 248 counts totaling $2.3 million. Individual investors were suing for their money. Her marriage broke up, and her life has been a nightmare since then.

Guillermo Seco, a Manhattan physician, was the first investor to sue Holzer to recover his money. After filing suit in March 1976, he and Holzer reached an out-of-court settlement in October of that year.

Shortly before the first set of indictments against her were issued in July 1977, three more investors filed an involuntary petition of bankruptcy against her to prevent her from transferring any of her assets to other creditors.

She was declared bankrupt on August 11, 1977, and a total of $12.9 million in claims against her have been made by other creditors since then.

Tepper told the jury during Holzer's trial last winter that Toyota denied any association with Holzer regarding the distributorship in Indonesia. The deeds to the land in Spain were "flagrant phonies," he added. "We checked with the Ministry of Justice in Spain, and the three notaries who recorded the deeds were not even listed. It just goes on and on."

It appears safe to at this point that Adela Holzer has hit rock bottom, at a depth unknown to most of us. But then she has seen terrian like this before-in 1954, for example when she arrived in New York with a lot of moxie, her jewels, and her first son still in her womb.

It is doubtful that she will remain down for long, though. Tepper said yesterday that she was soliciting funds on a radio talk show a month after her conviction. "They would never send such an innocent and good-hearted person like me to prison" he quoted her as saying on the program.

She also claimed to be writing a play and looking for a publisher for a book she is writing, tentatively titled "How to Cope with Crisis." CAPTION: Picture, Adela Holzer, producer of "Hair" and other stage hits; by Donal F. Holway for The Washington Post