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 A059778 #5 May 10 2013 12:44:34 %S A059778 1,0,-1,-1,-1,0,1,1,0,0,1,1,0,0,0,-1,-1,0,0,0,0,-1,-1,0,0,0,0,0,1,1,0, %T A059778 0,0,0,0,0,1,1,0,0,0,0,0,0,0,-1,-1,0,0,0,0,0,0,0,0,-1,-1,0,0,0,0,0,0, %U A059778 0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,1,1,0,0,0,0,0,0,0,0,0,0,0,-1,-1 %N A059778 Expansion of 1 / product((1+q^(2*n+3))/(1-q^(2*n+2)), n=0..inf). %C A059778 a(n) = (-1)^n*(t(n)-t(n-1)), n>0, where t(n) = A010054(n) is characteristic function of triangular numbers. - _Vladeta Jovovic_, Sep 22 2002 %D A059778 G. E. Andrews, Three-quadrant Ferrers graphs, Indian J. Math., 42 (No. 1, 2000), 1-7. %Y A059778 Cf. A059777. %K A059778 sign %O A059778 0,1 %A A059778 _N. J. A. Sloane_, Feb 21 2001