NEW YORK (AP) _ The Nikolais Dance Theater, started in 1948, and the Murray Louis Dance Company, dating from 1953, still exist, and now so does Nikolais and Louis Dance.

The combined group, with dancers and dances from both, is having its first season here, Oct. 17 through Nov. 5 at the Joyce Theater.

On Sunday afternoon, ''Segue,'' the first dance choreographed by Alwin Nikolais and Murray Louis together, had its premiere. It's unusual, but new works done separately by Nikolais and Louis on the same program were better.

''Ten Legs,'' choreographed by Louis, first seen in April in Montreal, is fun. Five dancers wear leotards of colorful geometric patterns over the torso with red legs. Dancers do new ways of lifting each other. They form a circle, put the weight on their shoulders and wave their legs in the air. They stack themselves up like the Pilobolus Dance Company. It's all light and amusing.

Nikolais' ''Intrados'' had its premiere last week at the Joyce. Edward Akio Taketa and Christopher Strauss are each inside a metal hoop, each hoop resting on a sturdy stand.

They curve their spines to fit the hoop, plant their feet and ''walk'' all the way around the hoop, inside. They stretch out of it, hang upside down from it, balance atop it, attain more positions in and around it than one would think possible. Taketa looks the happier of the two in his hoop. Both have amazing muscle control. It's like watching a high-wire act.

In ''Segue,'' subtitled ''Thru Memory's Eyes,'' a man scoots onto the stage on a low cart. He has a book from which the dancers presumably will come.

A program insert shows that the order of scenes is much different from the printed program. The two choreographers must have been working on ''Segue'' almost to curtain time. In ''Time and Remembrance,'' dancers in leotards the color of their skin dance in mechanical fashion. ''The Eccentric Aunt'' comes in looking like a round-faced Russian doll, swirling her cape. She suddenly dons a white animal mask, scoots forward like an old person or maybe an animal. It was interesting but hard to grasp the meaning.

Four women in big, round hats with wrap-around net veils which covered their bodies danced with feminine, slow, gentle movements. It looked like an avant-garde fashion show. ''Martial Arts'' was danced by four men dressed like nutcrackers, moving mechanically.

A clown, making much of his large hands, was followed by ''Ancestral Figures,'' four in ET-like masks who could have been emerging from the early earth's mud. Finally, the first figure returned, opened the book - of history or fairy tales - and the dancers went to sleep.

Lighting and electronic music for all three was done by Nikolais.

Next year, both companies and the joint company will tour.