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 A375651 #9 Aug 23 2024 02:11:42
%S A375651 1,1,3,13,61,341,2221,16045,127065,1097353,10231561,102133241,
%T A375651 1085537509,12228389629,145369356861,1816987580101,23804010114481,
%U A375651 325966118893457,4654236956576977,69138950655122929,1066449047096819901,17050138691821539781
%N A375651 Expansion of e.g.f. exp(x + x^2 * exp(x)).
%F A375651 a(n) = n! * Sum_{k=0..floor(n/2)} (k+1)^(n-2*k) / (k! * (n-2*k)!).
%o A375651 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x+x^2*exp(x))))
%o A375651 (PARI) a(n) = n!*sum(k=0, n\2, (k+1)^(n-2*k)/(k!*(n-2*k)!));
%Y A375651 Cf. A216507, A375652.
%K A375651 nonn
%O A375651 0,3
%A A375651 _Seiichi Manyama_, Aug 22 2024