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 A368267 #11 Dec 29 2023 06:03:55
%S A368267 1,4,24,206,2344,33322,568420,11312366,257293872,6583516946,
%T A368267 187173328444,5853594770806,199705444781512,7381068971010074,
%U A368267 293787494031046740,12528831526596461438,569923490454177217120,27545552296682691393058
%N A368267 Expansion of e.g.f. exp(2*x) / (1 - 2*x*exp(x)).
%F A368267 a(n) = n! * Sum_{k=0..n} 2^(n-k) * (n-k+2)^k / k!.
%F A368267 a(n) ~ n! / (4 * LambertW(1/2)^(n+2) * (LambertW(1/2) + 1)). - _Vaclav Kotesovec_, Dec 29 2023
%o A368267 (PARI) a(n) = n!*sum(k=0, n, 2^(n-k)*(n-k+2)^k/k!);
%Y A368267 Cf. A351762, A368236, A368268, A368269.
%K A368267 nonn,easy
%O A368267 0,2
%A A368267 _Seiichi Manyama_, Dec 19 2023