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%I #7 Mar 26 2018 20:34:56
%S 0,0,76,14392910
%N (1/(n!)^2) * number of ways to arrange the consecutive numbers 1...n^2 in an n X n matrix with determinant = 0.
%C The computation of a(5) seems to be currently (Jan 2008) out of reach (compare with A088021(5)).
%e 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.
%Y Cf. A001044, A046747, a(3)=A088215(0), a(4)=A136608(0), A221976.
%K hard,more,nonn
%O 1,3
%A _Hugo Pfoertner_, Jan 21 2008
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