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 A117257 #4 Mar 30 2012 18:36:56
%S A117257 1,1,-10,750,-328125,779296875,-9741210937500,630569458007812500,
%T A117257 -209368765354156494140625,354400253854691982269287109375,
%U A117257 -3045627181563759222626686096191406250,132489108572997338342247530817985534667968750
%N A117257 Column 0 of triangle A117256.
%F A117257 a(n) = [prod_{j=0..n-1} (1-5*j)]/n! * 5^(n*(n-1)/2).
%o A117257 (PARI) {a(n)=local(m=1,p=5,q=5,r=1);prod(j=0,n-1,m*r-p*j)/n!*q^(n*(n-1)/2)}
%K A117257 sign
%O A117257 0,3
%A A117257 _Paul D. Hanna_, Mar 14 2006