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 A356819 #13 Feb 23 2023 18:03:22
%S A356819 1,-1,-3,-1,41,239,229,-8401,-87151,-324577,3238541,70271519,
%T A356819 601086265,142860431,-81504662539,-1393683935281,-10777424809951,
%U A356819 63537986981183,3552608426329117,60283510555017023,441644419610814281,-6191820436867600081
%N A356819 Expansion of e.g.f. exp(-x * exp(2*x)).
%F A356819 G.f.: Sum_{k>=0} (-x)^k / (1 - 2*k*x)^(k+1).
%F A356819 a(n) = Sum_{k=0..n} (-1)^k * (2*k)^(n-k) * binomial(n,k).
%o A356819 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-x*exp(2*x))))
%o A356819 (PARI) my(N=30, x='x+O('x^N)); Vec(sum(k=0, N, (-x)^k/(1-2*k*x)^(k+1)))
%o A356819 (PARI) a(n) = sum(k=0, n, (-1)^k*(2*k)^(n-k)*binomial(n, k));
%Y A356819 Cf. A216689, A292952, A356812, A356820.
%K A356819 sign
%O A356819 0,3
%A A356819 _Seiichi Manyama_, Aug 29 2022