Invitations to Jimmy Carter's inauguration, which took place Jan. 20, are still being sent to thousands of campaign workers across the country, a Democratic National Committee official said yesterday.

Between 18,000 and 20,000 souvenir invitations have been addressed and will be mailed soon at a cost to the DNC of as much as $15,000, said field operations assistant Phil Chicola. They are left over from the inaugural committee's purchase of between 302,000 and 305,000 "y'all come" invitations, he said.

They are being sent to volunetters we knew couldn't come" Chicola said. "They're going to people who didn't really expected to get one."

A letter from DNC chairman Ken Curtis saying the souvenir invitation is being sent as "a token to express our gratitudes" is being enclosed.

Originally the inaugural committee said that 300,000 general invitations would be sent (as distinct from Carter's overall invitation to the whole country). Ultimately, about 270,000 were mailed before the event, inaugural committee executive director Larry Kieves said yesterday. The surplus was turned over to the DNC after Curtic became DNC chairman. The entire inaugural invitations operation was plagued with problems with people who should have received them not getting them and vice versa.

"The committee made some mistakes, the computer company was awful at data verification and whole lists (of names) were just lost," Kieves said. "It does seem late to be sending them out, though," he added. "I'd be embarrassed to get one now."