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 A375608 #8 Aug 21 2024 11:24:37
%S A375608 1,1,0,-6,-36,-120,240,8400,82320,362880,-3507840,-103783680,
%T A375608 -1268688960,-4843238400,175429013760,5052189542400,68016191443200,
%U A375608 55329155481600,-23284682272051200,-668640423164313600,-9013925405784499200,57340797108269875200
%N A375608 Expansion of e.g.f. 1 / (exp(x^2) - x).
%F A375608 a(n) = n! * Sum_{k=0..floor(n/2)} (-n+2*k-1)^k/k!.
%o A375608 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(exp(x^2)-x)))
%o A375608 (PARI) a(n) = n!*sum(k=0, n\2, (-n+2*k-1)^k/k!);
%Y A375608 Cf. A089148, A375609.
%Y A375608 Cf. A375394, A375604.
%K A375608 sign
%O A375608 0,4
%A A375608 _Seiichi Manyama_, Aug 21 2024