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 A356338 #8 Aug 05 2022 06:07:55
%S A356338 1,7,37,179,826,3703,16283,70619,303121,1290682,5460511,22981019,
%T A356338 96296552,402024497,1673116072,6944105579,28752345362,118801061059,
%U A356338 489959398840,2017339105514,8293732341134,34051489445365,139634028015269,571955737066307,2340402722605976,9567794393004816
%N A356338 a(n) = Sum_{k=1..n} binomial(2*n, n-k) * sigma(k).
%F A356338 a(n) ~ Pi^(3/2) * 4^(n-1) * sqrt(n) / 3.
%t A356338 Table[Sum[Binomial[2*n, n-k]*DivisorSigma[1, k], {k, 1, n}], {n, 1, 30}]
%o A356338 (PARI) a(n) = sum(k=1, n, binomial(2*n, n-k) * sigma(k)); \\ _Michel Marcus_, Aug 05 2022
%Y A356338 Cf. A000203, A024916, A185003, A351146.
%K A356338 nonn
%O A356338 1,2
%A A356338 _Vaclav Kotesovec_, Aug 04 2022