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 A352843 #15 Apr 15 2022 10:08:54
%S A352843 1,1,6,44,491,6597,110652,2144606,47988524,1206275925,33777572464,
%T A352843 1040200674416,34967153135940,1273241146218823,49928549099500206,
%U A352843 2097300313258417056,93953420539864844743,4470694981375022862697,225184078001798318202935
%N A352843 Expansion of e.g.f. exp(Sum_{k>=1} sigma_k(k) * x^k/k!).
%C A352843 Exponential transform of A023887.
%F A352843 a(0) = 1; a(n) = Sum_{k=1..n} sigma_k(k) * binomial(n-1,k-1) * a(n-k).
%t A352843 nmax = 20; CoefficientList[Series[E^(Sum[DivisorSigma[k, k]*x^k/k!, {k, 1, nmax}]), {x, 0, nmax}], x] * Range[0, nmax]! (* _Vaclav Kotesovec_, Apr 15 2022 *)
%o A352843 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=1, N, sigma(k, k)*x^k/k!))))
%o A352843 (PARI) a(n) = if(n==0, 1, sum(k=1, n, sigma(k, k)*binomial(n-1, k-1)*a(n-k)));
%Y A352843 Cf. A295739, A274804, A352694.
%Y A352843 Cf. A023887, A352841, A352842, A202477.
%K A352843 nonn
%O A352843 0,3
%A A352843 _Seiichi Manyama_, Apr 05 2022