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 A087539 #4 Mar 30 2012 18:41:20 %S A087539 0,0,1,2,3,5,7,10,12,15,18,22,26,30,35,40,46,51,57,63,70,77,84,92,100, %T A087539 109,117,126,135,145,155,165,176,187,199,210,222,234,247,260,273,287, %U A087539 301,316,330,345,360,376,392,408,425,442,460,477,495,513 %N A087539 First differences of A011849. %F A087539 [ C(n+1, 3)/3 ] - [ C(n, 3)/3 ]. %F A087539 G.f.: [x^3(1-x+x^2)(1-x^2+x^3)]/[(1-x)^3(1+x^3+x^6)]. %K A087539 nonn,easy %O A087539 1,4 %A A087539 _Ralf Stephan_, Oct 24 2003