A278925 a(n) = permanent M_n where M_n is the n X n matrix m(i,j) = i^3 + j^3.

1, 2, 113, 38736, 46311652, 143820883800, 966462062838180, 12412328008727861760, 278484670746890475310656, 10197331743850942940587152000, 577793817845799602600135280168000, 48534819511412868687827815575204633600, 5834998526939444017550860154062183732711680

Offset: 0

Author

Vaclav Kotesovec, Dec 01 2016

Keywords

• nonn

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..36

Crossrefs

Cf. A204249, A278847, A278926.

Programs

Maple

with(LinearAlgebra):
a:= n-> `if`(n=0, 1, Permanent(Matrix(n, (i, j)-> i^3+j^3))):
seq(a(n), n=0..16);

Mathematica

Flatten[{1, Table[Permanent[Table[i^3+j^3, {i, 1, n}, {j, 1, n}]], {n, 1, 15}]}]

PARI

{a(n) = matpermanent(matrix(n, n, i, j, i^3+j^3))}
for(n=0, 20, print1(a(n), ", ")) \\ Vaclav Kotesovec, Dec 21 2018

Formula

a(n) ~ c * d^n * n!^4 / n^(3/2), where d = 6.538385468679... and c = 0.84959670006...