Number of permutations i_1, ..., i_n of 1, ..., n with i_1 = 1 and i_n = n such that i_1+2*i_2, i_2+2*i_3, ..., i_{n-1}+2*i_n, i_n+2*i_1 are pairwise distinct modulo n.
A227399
Number of permutations i_1, ..., i_n of 1, ..., n with i_1 = 1 and i_n = n such that i_1+2*i_2, i_2+2*i_3, ..., i_{n-1}+2*i_n, i_n+2*i_1 are pairwise distinct modulo n.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =1a(4) =1a(5) =2a(6) =8a(7) =20a(8) =18a(9) =166a(10) =397a(11) =2788a(12) =5448a(13) =78102a(14) =149562a(15) =2576896a(16) =6003432a(17) =91012592a(18) =257246112a(19) =5272355344a(20) =12450552690
External references
- oeis: A227399