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 A341106 #10 Dec 10 2023 17:26:43
%S A341106 1,-1,0,6,-12,-144,1080,5184,-127008,95904,19077120,-154929024,
%T A341106 -3210337152,70284900096,391453171200,-30354545511936,153830450875392,
%U A341106 13189520200402944,-244127117929789440,-5109022268709986304,237988748560571301888,571783124036801765376
%N A341106 a(n) = 2^n*E2poly(n, -1/2), where E2poly(n, x) = Sum_{k=0..n} A340556(n, k)*x^k, are the second-order Eulerian polynomials.
%p A341106 E2poly := (n, x) -> add(A340556(n, k)*x^k, k = 0..n):
%p A341106 seq(2^n*E2poly(n, -1/2), n = 0..21);
%p A341106 # By series reversion:
%p A341106 serrev := proc(gf, len) series(gf, y, len);
%p A341106 gfun:-seriestoseries(%, 'revogf'); gfun:-seriestolist(%);
%p A341106 gfun:-listtolist(%, 'Laplace'); subsop(1 = NULL, %) end:
%p A341106 gf := (6*y + exp(3*y) - 1)/9: serrev(gf, 23);
%t A341106 R := 22; f[y_] := (6y + Exp[3y] - 1)/9;
%t A341106 S := InverseSeries[Series[f[y], {y, 0, R}], x];
%t A341106 Drop[CoefficientList[S, x] Table[n!, {n, 0, R}], 1]
%Y A341106 Cf. A340556.
%K A341106 sign
%O A341106 0,4
%A A341106 _Peter Luschny_, Feb 13 2021