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 A372216 #11 Apr 24 2024 05:44:34
%S A372216 1,4,25,168,1218,9240,72501,583440,4789070,39940888,337490426,
%T A372216 2883046320,24858176900,216046612080,1890737146125,16647522481440,
%U A372216 147365806700310,1310740896927000,11708311265437710,104989351441019760
%N A372216 Product of n-th Pell number and n-th Catalan number: a(n) = A000129(n)*A000108(n).
%F A372216 G.f.: 1/(2*x)-sqrt(sqrt(-16*x^2-8*x+1)+4*x+3)/(4*x).
%F A372216 D-finite with recurrence +n*(n+1)*a(n) -4*n*(2*n-1)*a(n-1) -4*(2*n-1)*(2*n-3)*a(n-2)=0. - _R. J. Mathar_, Apr 24 2024
%t A372216 CoefficientList[Series[1/(2*x)-Sqrt[Sqrt[-16*x^2-8*x+1]+4*x+3]/(4*x),{x,0,20}],x] (* _Stefano Spezia_, Apr 22 2024 *)
%Y A372216 Cf. A000108, A000129.
%K A372216 nonn
%O A372216 1,2
%A A372216 _Vladimir Kruchinin_, Apr 22 2024