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 A109963 #3 Mar 30 2012 18:59:08
%S A109963 1,-1,5,-27,171,-1178,8582,-65029,507317,-4047608,32874104,-270893586,
%T A109963 2259210814,-19032956491,161735556091,-1384662302187,11931865642979,
%U A109963 -103409449621325,900778907303037,-7882176975668156,69253864680597564,-610717827031587856
%N A109963 Diagonal sums of number triangle A109962.
%F A109963 G.f.: g/(1-f) where f/(1-f)^4=x and g=1/(1-f); a(n)=(-1)^n*sum{k=0..floor(n/2), ((4k+1)/(3n-2k+1))*binomial(4n-4k, n-2k)}.
%K A109963 easy,sign
%O A109963 0,3
%A A109963 _Paul Barry_, Jul 06 2005