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%I #7 Sep 06 2013 02:05:08
%S 378,5133128,81705087744,983771662124160,13027612739061516288,
%T 180842352214339004973056,2505372582582745606695616512,
%U 35065654463193295271305370959872,495605164965018396615832445084368896
%N Number of pairs of orthogonal (-2,5) vectors of length 7*n.
%C Row 8 of A225987.
%H R. H. Hardin, <a href="/A225994/b225994.txt">Table of n, a(n) for n = 1..78</a>
%e Some solutions for n=1
%e .-2..5...-2..5...-2..5...-2..5....5..5...-2..5....5..5....5..5...-2..5...-2..5
%e .-2..5....5..5....5.-2...-2..5....5..5....5..5...-2..5...-2..5....5..5....5.-2
%e ..5..5...-2..5....5.-2....5.-2...-2..5....5.-2....5.-2....5.-2....5.-2....5..5
%e .-2..5...-2..5....5.-2....5.-2...-2..5....5..5...-2..5....5..5....5.-2....5..5
%e ..5.-2....5.-2....5.-2....5..5....5.-2....5.-2...-2..5...-2..5....5.-2...-2..5
%e ..5..5....5..5....5..5....5.-2...-2..5....5.-2....5.-2....5.-2....5.-2...-2..5
%e ..5.-2....5.-2....5..5....5..5...-2..5...-2..5....5..5....5.-2....5..5...-2..5
%K nonn
%O 1,1
%A _R. H. Hardin_, May 22 2013