Triangle read by rows: T(n,k) is the number of permutations of length n that have k same elements at the same positions with its inverse permutation for 0 <= k <= n.

A344901

Triangle read by rows: T(n,k) is the number of permutations of length n that have k same elements at the same positions with its inverse permutation for 0 <= k <= n.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =0a(4) =0a(5) =2a(6) =2a(7) =0a(8) =0a(9) =4a(10) =6a(11) =8a(12) =0a(13) =0a(14) =10a(15) =24a(16) =30a(17) =40a(18) =0a(19) =0a(20) =26a(21) =160a(22) =144a(23) =180a(24) =160a(25) =0a(26) =0a(27) =76a(28) =1140a(29) =1120

External references