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 A100236 #3 Mar 30 2012 18:36:44
%S A100236 1,4,26,139,726,3774,19601,101784,528526,2744419,14250626,73997554,
%T A100236 384238401,1995189564,10360186226,53796120699,279340789726,
%U A100236 1450500069334,7531841136401,39109705751344,203080369893126
%N A100236 Main diagonal of triangle A100235.
%F A100236 a(n) = 5*a(n-1) + a(n-2) + 5 for n>1, with a(0)=1, a(1)=4. G.f.: Sum_{n>=1} a(n)*x^n/n = log((1-x)/(1-5*x-x^2)).
%o A100236 (PARI) a(n)=if(n==0,1,n*polcoeff(log((1-x)/(1-5*x-x^2)+x*O(x^n)),n))
%Y A100236 Cf. A100233, A100235.
%Y A100236 Equals A087130(n) - 1.
%K A100236 nonn
%O A100236 0,2
%A A100236 _Paul D. Hanna_, Nov 30 2004