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 A091548 #3 Oct 12 2012 14:40:20 %S A091548 1,1,-1,-53,-1083,-24099,-120477,115958039,30323462809,7554183583865, %T A091548 2000735772375143,483441809221224835,-15004002104132799283, %U A091548 -243176330287496140346187,-424738050855195910944014901,-660294012298780945217254277745 %N A091548 Alternating row sums of triangle A091543. %F A091548 a(n)=sum(A091543(n, m)*(-1)^m, m=0..n-1), n>=1. %K A091548 sign,easy %O A091548 1,4 %A A091548 _Wolfdieter Lang_, Feb 13 2004