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 A156172 #2 Mar 30 2012 16:51:15 %S A156172 2,14,610,66734,13631170,4474847054,2154541552930,1430306187579374, %T A156172 1252111529306645890,1397549490970710103694,1937106722774840873390050, %U A156172 3264361741756845694953780014,6572644038805857912224455865410,15583184923914619905634967412688334,42971525874172716914734880462487351970 %N A156172 Twice A002437. %C A156172 Suggested by analogy with A000191. %p A156172 Q:=proc(n) option remember; if n=0 then RETURN(1); else RETURN(expand((u^2+1)*diff(Q(n-1),u)+u*Q(n-1))); fi; end; %p A156172 [seq(2*subs(u=sqrt(3),Q(2*n)),n=0..25)]; %K A156172 nonn %O A156172 0,1 %A A156172 _N. J. A. Sloane_, Nov 06 2009