Number of permutations of 3 copies of 1..n with all adjacent differences <= 2 in absolute value.

A177292

Number of permutations of 3 copies of 1..n with all adjacent differences <= 2 in absolute value.

Terms

    a(0) =1a(1) =1a(2) =20a(3) =1680a(4) =51240a(5) =1173512a(6) =31006978a(7) =788946320a(8) =18721725280a(9) =435630242080

External references