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 A362848 #14 Oct 09 2023 14:30:14
%S A362848 1,4,121,11376,2165689,689873284,330204013569,221470234531456,
%T A362848 198160750081637521,228040136335670652324,328106086348844570538409,
%U A362848 577082259304437657893671984,1218130815379359944856599793801,3039062974890293661892991548863076
%N A362848 a(n) = Sum_{k=0..n} 4^k * Gamma(n + k + 1/2) / Gamma(n - k + 1/2). Row sums of A362847.
%F A362848 a(n) = Sum_{k=0..n} (2*(n + k) - 1)!! / (2*(n - k) - 1)!!. - _Detlef Meya_, Oct 09 2023
%F A362848 a(n) ~ 2^(4*n + 1/2) * n^(2*n) / exp(2*n). - _Vaclav Kotesovec_, Oct 09 2023
%t A362848 a[n_]:= Sum[(2*(n+k)-1)!!/(2*(n-k)-1)!!,{k,0,n}];Flatten[Table[a[n],{n,0,13}]] (* _Detlef Meya_, Oct 09 2023 *)
%Y A362848 Cf. A362847.
%K A362848 nonn
%O A362848 0,2
%A A362848 _Peter Luschny_, May 05 2023