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 A087781 #7 Mar 31 2012 13:20:50 %S A087781 1,0,0,0,1,0,0,0,0,0,2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,2,0,2,0,0,0, %T A087781 0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,2,0,0,0,2,0,2,0,0,0,0,0,0,0, %U A087781 0,0,2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,2,0,0,0,0,0,2,0,0,0,0 %N A087781 Number of non-congruent solutions to x^2 - x - 1 == 0 mod n. %C A087781 Sequence A089270 gives the positions of the nonzero terms. The term a(n) gives the number of primitive solutions (x,y) of the equation x^2 + xy - y^2 = n. %H A087781 T. D. Noe, <a href="/A087781/b087781.txt">Table of n, a(n) for n=1..10000</a> %Y A087781 Cf. A000086, A034444. %K A087781 mult,nonn %O A087781 1,11 %A A087781 Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 06 2003 %E A087781 More terms from _David Wasserman_, Jun 17 2005