A204440 Permanent of the n-th principal submatrix of A204439.

1, 1, 1, 2, 6, 20, 80, 384, 2016, 12096, 82080, 597888, 4783104, 41886720, 389145600, 3891456000, 41803776000, 472283136000, 5667397632000, 72153317376000, 959814696960000, 13437405757440000, 197840194965504000, 3028176742219776000, 48450827875516416000

Offset: 0

Author

Clark Kimberling, Jan 15 2012

Keywords

• nonn

Comments

Also the number of permutations pi in S_n such that pi(i) + i != 1 (mod 3) for all i. - Peter Kagey, Jan 25 2021

Crossrefs

Cf. A204239, A204435.

Programs

Mathematica

f[i_, j_] := Mod[(2 + i + j)^2, 3];
m[n_] := Table[f[i, j], {i, 1, n}, {j, 1, n}]
TableForm[m[8]] (* 8x8 principal submatrix *)
Flatten[Table[f[i, n + 1 - i],
  {n, 1, 14}, {i, 1, n}]]           (* A204439 *)
Join[{1},Table[Permanent[m[n]], {n, 1, 22}]]  (* A204440 *)

Extensions

Typo in name corrected by Michel Marcus, Nov 11 2016

a(0) and a(23)-a(24) from Pontus von Brömssen, Jan 29 2021