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 A091751 #3 Oct 12 2012 14:40:20 %S A091751 1,29,2899,625381,235735025,137662456849,115219635641083, %T A091751 130892567494940777,193870813073375001313,362981045220391075931461, %U A091751 838251579579056365127865923,2340586894706172958195272669517,7772441664087128321443493161452817 %N A091751 Alternating row sums of array A091747 (generalized Stirling2 array (7,2)). %C A091751 The first negative term is the 159 digit number a(43)=-2116278545846...33655549. %F A091751 a(n)=sum(A091747(n, k)*(-1)^k, k=2..2*n), n>=1. %Y A091751 Cf. A091749 (row sums of A091747). %K A091751 sign,easy %O A091751 1,2 %A A091751 _Wolfdieter Lang_, Feb 27 2004