A204252 Permanent of the n-th principal submatrix of A201208 (in square format).

1, 5, 18, 132, 876, 8820, 85392, 1106496, 14057280, 223560000, 3513456000, 66305952000, 1241430624000, 27127003680000, 589395356928000, 14638710417408000, 362021985626112000, 10073602372700160000, 279369787588448256000, 8609476463579013120000, 264609942011693752320000

Offset

1,2

Links

Vaclav Kotesovec, Table of n, a(n) for n = 1..30

Maple

a:= n-> LinearAlgebra[Permanent](Matrix(n, (i, j)-> 1+irem(i+j, 2))):
seq(a(n), n=1..20);  # Alois P. Heinz, Apr 23 2025

Mathematica

f[i_, j_] := 1 + Mod[i + j, 2];
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, 12}, {i, 1, n}]] (* A201208 in square format *)
Permanent[m_] :=
  With[{a = Array[x, Length[m]]},
   Coefficient[Times @@ (m.a), Times @@ a]];
Table[Permanent[m[n]], {n, 1, 20}]    (* A204252 *)

Prog

(PARI) a(n) = {matpermanent(matrix(n, n, i, j, 1 + (i+j)%2))};
for(n=1, 25, print1(a(n), ", ")) \\ Vaclav Kotesovec, Apr 21 2025

Crossrefs

Cf. A201208, A383212.

Sequence in context: A009365 A140296 A278172 * A281564 A291356 A091059

Adjacent sequences: A204249 A204250 A204251 * A204253 A204254 A204255

Keyword

nonn

Author

Clark Kimberling, Jan 14 2012

Extensions

a(20)-a(21) from Pontus von Brömssen, Mar 03 2024

Status

approved