D.C. undercover narcotics detectives said yesterday that they paid $133,000 in $100 bills to a Colorado businessman at a Georgetown motel, and then seized an estimated $1 million worth of cocaine--almost 4 1/2 pounds.

Authorities called it one of the largest narcotics confiscations in recent years.

Minutes after the Georgetown arrest, a combined force of District, Arlington and federal drug agents arrested two other men outside an Arlington motel on charges of conspiring in the case. More than two pounds of cocaine was seized after these arrests, police said.

Capt. James Nestore, head of the D.C. narcotics squad, said the arrests climaxed a three-month investigation that led first to the arrest of Judah R. Lyons, 33, of Lyons, Colo., on charges of intent to distribute cocaine.

Police said Lyons arrived at Dulles International Airport Tuesday afternoon and--with undercover detectives following him--met in Arlington with two other men, Denny Lee Williamson, 31, of La Mirada, Calif., and Timothy J. Marfisi, 31, of Miami Springs, Fla.

Yesterday, police said, detectives brought a briefcase filled with $100 bills to Lyons' room at a motel they would not identify. There, police said, they seized two kilos of cocaine and a loaded handgun.

D.C. detectives then radioed detectives waiting outside the Arlington motel where Williamson and Marfisi were staying. The two men were arrested and a third kilo of cocaine was seized from a car that police said was used to bring the cocaine to the Washington area from Florida.

Lyons, who listed his occupation as a horse trainer and who police said had interests in an oil well and several other businesses, will be arraigned today in Superior Court. Williamson and Marfisi were arraigned before a U.S. magistrate and were ordered held in $25,000 and $250,000 bond, respectively.