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 A103973 #16 Nov 19 2021 10:38:58
%S A103973 1,2,4,4,24,16,160,80,1120,448,8064,2688,59136,16896,439296,109824,
%T A103973 3294720,732160,24893440,4978688,189190144,34398208,1444724736,
%U A103973 240787456,11076222976,1704034304,85201715200,12171673600,657270374400
%N A103973 Expansion of (sqrt(1-8*x^2)+8*x^2+2*x-1)/(2*x*sqrt(1-8*x^2)).
%F A103973 G.f.: 1/sqrt(1-8*x^2)+(1-sqrt(1-8*x^2))/(2*x).
%F A103973 a(n) = sum{k=0..floor(n/2), 2^(n-k) * A000108(k) * C(k+1, n-k)}.
%F A103973 Conjecture D-finite with recurrence: 11*n*(n+1)*a(n)+4*n*(4*n+1)*a(n-1) +8*(27-11*n^2)*a(n-2) -32*(4*n+9)*(n-3)*a(n-3)=0. - _R. J. Mathar_, Nov 09 2012
%F A103973 a(n) ~ 2^((3*n + 1)/2) / sqrt(Pi*n) if n is even and a(n) ~ 2^((3*n + 2)/2) / (sqrt(Pi)*n^(3/2)) if n is odd. - _Vaclav Kotesovec_, Nov 19 2021
%Y A103973 Cf. A025225, A059304.
%K A103973 easy,nonn
%O A103973 0,2
%A A103973 _Paul Barry_, Feb 23 2005