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 A225989 #7 Sep 06 2013 02:04:54 %S A225989 20,3192,652784,134432480,28244153600,6052498776192,1314942362273280, %T A225989 288501497813552640,63776322167821168640,14182989297327325110272, %U A225989 3169467786802943379238912,711136363409644515952173056 %N A225989 Number of pairs of orthogonal (-1,3) vectors of length 4*n. %C A225989 Row 3 of A225987. %H A225989 R. H. Hardin, <a href="/A225989/b225989.txt">Table of n, a(n) for n = 1..145</a> %e A225989 Some solutions for n=1 %e A225989 .-1..3...-1..3....3..3...-1..3...-1..3...-1..3...-1..3...-1.-1....3..3...-1..3 %e A225989 ..3..3...-1..3...-1..3....3..3...-1..3....3.-1...-1..3...-1.-1...-1..3....3.-1 %e A225989 .-1..3....3..3...-1..3....3.-1....3.-1....3..3...-1..3...-1.-1....3.-1....3..3 %e A225989 ..3.-1....3.-1....3.-1...-1..3....3..3...-1..3....3..3...-1..3....3.-1....3.-1 %K A225989 nonn %O A225989 1,1 %A A225989 _R. H. Hardin_, May 22 2013