Pianist George Spicka has a bright idea, but so far he's had trouble convincing America's Mensas that they should join his M-Provisers, a special-interest jazz organization. Mensas, of course, are those who are supposed to be in the upper 98 percent of the I.Q. range (there are 50,000 members in the American chapter). "But only seven people have responded so far," Spicka says. Two of them are also Washingtonians, singer Dianne Davis and David Savage, a songwriter who doubles on cornet and keyboards.

Spicka, who has composed close to 150 jazz pieces, is not giving up: While Mensa has been around more than 20 years, his group is only 8 months old. "What I was hoping to do -- and it hasn't really turned out this way -- was to find people who were my level, seriously pursuing jazz, especially people who had already gotten into a higher level, with agents or managers. I wanted to develop a network of people who would be interested in promoting Mensa jazz artists."

Tomorrow, Spicka and his Jazz Ensemble will perform two concerts at the Prince George's Publick Playhouse in Hyattsville. The first part of the shows will feature an instrumental trio, with bassist Larry Kinling and drummer Pete Chauvette, doing a mix of originals and standards or modern jazz tunes, followed by vocalist Charlene De Gault. The concerts take place Monday at 10:30 a.m. and 1:30 p.m. (Call 277-1711.)