This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A225991 #10 Apr 02 2014 19:20:33 %S A225991 45,26010,21594300,15593341800,11432293516320,8690522384325600, %T A225991 6699690552347865600,5206881575348541978240,4077143683681515029088000, %U A225991 3212142498665023117259125760,2542945288539007875744064972800 %N A225991 Number of pairs of orthogonal (-1,4) vectors of length 5*n. %C A225991 Row 5 of A225987. %H A225991 R. H. Hardin, <a href="/A225991/b225991.txt">Table of n, a(n) for n = 1..107</a> %e A225991 Some solutions for n=1 %e A225991 .-1..4...-1..4....4..4...-1..4...-1..4...-1.-1...-1..4....4..4...-1..4...-1..4 %e A225991 ..4..4...-1..4...-1..4....4.-1....4..4...-1.-1....4.-1...-1..4....4.-1....4..4 %e A225991 ..4.-1...-1..4...-1..4....4.-1...-1..4...-1.-1....4..4...-1..4....4..4...-1..4 %e A225991 ..4.-1....4..4...-1..4...-1..4...-1..4...-1..4...-1..4....4.-1....4.-1...-1..4 %e A225991 .-1..4...-1..4...-1..4....4..4...-1..4...-1.-1....4.-1....4.-1...-1..4....4.-1 %K A225991 nonn %O A225991 1,1 %A A225991 _R. H. Hardin_, May 22 2013