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 A367874 #15 Feb 03 2024 10:15:20
%S A367874 1,3,11,48,241,1358,8445,57256,419233,3290202,27507349,243731084,
%T A367874 2278919697,22402234390,230781192301,2484462888312,27880896280513,
%U A367874 325432611292082,3943062342781605,49504837209940612,642982531293731761,8626753575445207278
%N A367874 Expansion of e.g.f. exp(x * (2 + exp(x))).
%F A367874 G.f.: Sum_{k>=0} x^k / (1 - (k+2)*x)^(k+1).
%F A367874 a(n) = Sum_{k=0..n} (k+2)^(n-k) * binomial(n,k).
%F A367874 a(0) = 1; a(n) = 2 * a(n-1) + Sum_{k=1..n} binomial(n-1,k-1) * k * a(n-k). - _Ilya Gutkovskiy_, Feb 02 2024
%o A367874 (PARI) a(n) = sum(k=0, n, (k+2)^(n-k)*binomial(n, k));
%Y A367874 Cf. A000248, A080108, A367875.
%Y A367874 Cf. A240165.
%K A367874 nonn,easy
%O A367874 0,2
%A A367874 _Seiichi Manyama_, Dec 03 2023