A136609 (1/(n!)^2) * number of ways to arrange the consecutive numbers 1...n^2 in an n X n matrix with determinant = 0.

0, 0, 76, 14392910

Offset: 1

Author

Hugo Pfoertner, Jan 21 2008

Keywords

• hard
• more
• nonn

Comments

The computation of a(5) seems to be currently (Jan 2008) out of reach (compare with A088021(5)).

Examples

			a(1)=0 because det((1))/=0, a(2)=0, because the only possible determinants of a matrix with elements {1,2,3,4} are +-2, +-5 and +-10.
		

Crossrefs

Cf. A001044, A046747, a(3)=A088215(0), a(4)=A136608(0), A221976.