A195890 - OEIS

%I #5 Dec 18 2015 18:17:46

%S 1,1,13,1105,680115,3204150229

%N Number of lower triangles of an n X n integer array with all row and column sums zero and all row and column sums of squares <=72

%C Column 6 of A195892

%e Some solutions for n=4

%e ..0........0........0........0........0........0........0........0

%e ..4-4......0.0......5-5......4-4.....-1.1......5-5......0.0......4-4

%e .-3.4-1....4.1-5...-4.5-1...-6.1.5....1.4-5...-6.6.0...-3-1.4....2-2.0

%e .-1.0.1.0.-4-1.5.0.-1.0.1.0..2.3-5.0..0-5.5.0..1-1.0.0..3.1-4.0.-6.6.0.0

%K nonn

%O 1,3

%A _R. H. Hardin_ Sep 24 2011