%I #7 Sep 06 2013 02:05:04
%S 102,211332,720120000,1722187940880,4204143930847392,
%T 11097567635368456704,29480432084171748705792,
%U 78401556201196275000295680,210537848971493804380009055232,569368618586592872585662539389952
%N Number of pairs of orthogonal (-1,5) vectors of length 6*n.
%C Row 7 of A225987.
%H R. H. Hardin, <a href="/A225993/b225993.txt">Table of n, a(n) for n = 1..91</a>
%e Some solutions for n=1
%e .-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5
%e .-1..5...-1..5...-1.-1...-1..5....5.-1...-1..5...-1..5....5..5....5.-1....5.-1
%e .-1..5...-1..5...-1.-1....5.-1....5.-1...-1..5....5..5...-1..5...-1..5....5..5
%e ..5..5...-1..5...-1.-1....5..5...-1..5....5.-1...-1..5...-1..5...-1..5...-1..5
%e .-1..5....5..5...-1.-1...-1..5...-1..5....5.-1...-1..5....5.-1....5..5....5.-1
%e .-1..5....5.-1...-1.-1...-1..5....5..5....5..5....5.-1...-1..5....5.-1....5.-1
%K nonn
%O 1,1
%A _R. H. Hardin_, May 22 2013