a(n) is the number of permutations of [1..n] that have the same number of inversions as non-inversions.

A316775

a(n) is the number of permutations of [1..n] that have the same number of inversions as non-inversions.

Terms

    a(0) =1a(1) =1a(2) =0a(3) =0a(4) =6a(5) =22a(6) =0a(7) =0a(8) =3836a(9) =29228a(10) =0a(11) =0a(12) =25598186a(13) =296643390a(14) =0a(15) =0a(16) =738680521142a(18) =0a(19) =0a(22) =0a(23) =0a(26) =0a(27) =0

External references