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 A375653 #9 Aug 23 2024 02:12:14
%S A375653 1,1,3,13,49,321,1891,13693,113793,942049,9428131,93837261,1043918833,
%T A375653 12318170593,151123106499,2024107965181,27672074520961,
%U A375653 406722703307073,6188268876372163,98499148173678349,1645657615850089521,28317883192163927041
%N A375653 Expansion of e.g.f. exp(x^2 + x * exp(x^2)).
%F A375653 a(n) = n! * Sum_{k=0..floor(n/2)} (n-2*k+1)^k / (k! * (n-2*k)!).
%o A375653 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x^2+x*exp(x^2))))
%o A375653 (PARI) a(n) = n!*sum(k=0, n\2, (n-2*k+1)^k/(k!*(n-2*k)!));
%Y A375653 Cf. A216688, A375654.
%Y A375653 Cf. A375604.
%K A375653 nonn
%O A375653 0,3
%A A375653 _Seiichi Manyama_, Aug 22 2024