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 A355365 #8 Mar 19 2023 05:47:37
%S A355365 1,3,54,1360,41405,1404102,51126740,1957600876,77812428681,
%T A355365 3183756066040,133302637049516,5687179333193904,246453229359401883,
%U A355365 10821674290217357756,480561612716912592360,21549547977144582750304,974600584933918611940825,44409401763058366474029057
%N A355365 Central terms of A355360; a(n) = A355360(2*n,n).
%H A355365 Paul D. Hanna, <a href="/A355365/b355365.txt">Table of n, a(n) for n = 0..60</a>
%F A355365 a(n) ~ c * d^n / n^2, where d = 51.3157915205364... and c = 0.1124829020506... - _Vaclav Kotesovec_, Mar 19 2023
%o A355365 (PARI) {a(n) = my(A=[1,y],t); for(i=1,2*n, A=concat(A,0); t = ceil(sqrt(2*(#A)+9));
%o A355365 A[#A] = polcoeff( x*y*Ser(A) - sum(m=-t,t, (-1)^m*x^(m*(m+1)/2)*Ser(A)^m ), #A-1));polcoeff(A[2*n+1],n,y)}
%o A355365 for(n=0,30, print1( a(n),", "));
%Y A355365 Cf. A355360, A355361, A355362, A355363, A355364.
%K A355365 nonn
%O A355365 0,2
%A A355365 _Paul D. Hanna_, Jul 19 2022