Number of cyclic arrangements (up to direction) of numbers 1,2,...,n such that any two neighbors are coprime.

A242529

Number of cyclic arrangements (up to direction) of numbers 1,2,...,n such that any two neighbors are coprime.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =2a(6) =36a(7) =36a(8) =360a(9) =288a(10) =11016a(11) =3888a(12) =238464a(13) =200448a(14) =3176496a(15) =4257792a(16) =402573312a(17) =139511808a(18) =18240768000a(19) =11813990400a(20) =440506183680a(21) =532754620416

External references