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 A117255 #4 Mar 30 2012 18:36:56
%S A117255 1,1,-6,224,-39424,30277632,-98180268032,1321338098679808,
%T A117255 -73064711504598663168,16493270769791857518968832,
%U A117255 -15132641904367108441083979235328,56258298143912014448000446346897129472,-845539117695226477286180063077230730209656832
%N A117255 Column 0 of triangle A117254.
%F A117255 a(n) = [prod_{j=0..n-1} (1-4*j)]/n! * 4^(n*(n-1)/2).
%o A117255 (PARI) {a(n)=local(m=1,p=4,q=4,r=1);prod(j=0,n-1,m*r-p*j)/n!*q^(n*(n-1)/2)}
%K A117255 sign
%O A117255 0,3
%A A117255 _Paul D. Hanna_, Mar 14 2006