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 A225986 #5 May 22 2013 12:59:33 %S A225986 4,9,20,60,45,420,102,378,1120,3024,231,22176,520,2376,8160,23760, %T A225986 63360,164736,1161,21780,185328,1235520,2570,14190,188760,544544, %U A225986 3660800,9335040,5643,147576,11202048,70946304,12300,80028,374192,1408680 %N A225986 Number of pairs of orthogonal (-x,y) vectors of length 1*(x+y), where x/y is the n-th rational <= 1, ordered first by y and then x, e.g. 1/1, 1/2, 1/3, 2/3, 1/4, 3/4 ... %C A225986 Column 1 of A225987 %H A225986 R. H. Hardin, <a href="/A225986/b225986.txt">Table of n, a(n) for n = 1..210</a> %e A225986 All solutions for n=1 %e A225986 .-1..1...-1.-1...-1..1....1..1 %e A225986 .-1.-1...-1..1....1..1...-1..1 %K A225986 nonn %O A225986 1,1 %A A225986 _R. H. Hardin_ May 22 2013