A383212 a(n) = permanent of the n-th principal submatrix of the rectangular array whose odd-numbered rows are (2,1,2,1,2,1,2,1,...) and even-numbered rows are (1,2,1,2,1,2,1,2,...).

1, 2, 5, 24, 132, 1032, 8820, 95616, 1106496, 15327360, 223560000, 3768768000, 66305952000, 1316927808000, 27127003680000, 620221722624000, 14638710417408000, 378633583448064000, 10073602372700160000, 290788929384726528000, 8609476463579013120000, 274361332654900592640000, 8946658680536444313600000

Offset: 0

Author

Clark Kimberling, Apr 19 2025

Keywords

• nonn

Crossrefs

Cf. A204252.

Programs

Maple

1, seq(LinearAlgebra:-Permanent(Matrix(n,n,(i,j) -> 1 + (i+j+1 mod 2))), n=1..22); # Robert Israel, Apr 23 2025

Mathematica

a[i_, j_] := If[EvenQ[i + j], 2, 1];
m[n_] := Table[a[i, j], {i, 1, n}, {j, 1, n}];
Join[{1}, Table[Permanent[m[n]], {n, 1, 19}]]

PARI

a(n) = {matpermanent(matrix(n, n, i, j, 2 - (i+j)%2))};
for(n=0, 25, print1(a(n), ", ")) \\ Vaclav Kotesovec, Apr 21 2025

Extensions

a(20)-a(22) from Vaclav Kotesovec, Apr 21 2025