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 A120896 #3 Mar 30 2012 18:36:58 %S A120896 1,1,2,5,10,27,73,189,518,1413,3857,10707,29804,83365,234665,662654, %T A120896 1878059,5341302,15231940,43552610,124829236,358537455,1031835260, %U A120896 2974872009,8590929683,24847042484,71964879243,208704926659 %N A120896 Central terms of triangle A120894 (cascadence of 1+x+x^2). %Y A120896 Cf. A120894, A120895, A120897. %K A120896 nonn %O A120896 0,3 %A A120896 _Paul D. Hanna_, Jul 14 2006