A195891 - OEIS

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

%S 1,1,15,1695,1686561,15120998539

%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 <=98

%C Column 7 of A195892

%e Some solutions for n=4

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

%e .-3.3.....-3.3......2-2.....-5.5......2-2.....-3.3......1-1......5-5

%e ..5.1-6....7.0-7...-5.6-1....7.0-7...-3.6-3...-3-2.5....4-4.0....0.7-7

%e .-2-4.6.0.-4-3.7.0..3-4.1.0.-2-5.7.0..1-4.3.0..6-1-5.0.-5.5.0.0.-5-2.7.0

%K nonn

%O 1,3

%A _R. H. Hardin_ Sep 24 2011