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 A368017 #8 Dec 08 2023 09:57:01
%S A368017 1,-2,-4,14,144,286,-5080,-61058,-186144,4016958,73395928,468915102,
%T A368017 -4728823088,-167453193314,-2051810224568,-406640603074,
%U A368017 533831885402048,11987797433266302,110763307665075640,-1459040819952150178,-80503810962755821904
%N A368017 Expansion of e.g.f. exp(exp(x) - exp(3*x)).
%F A368017 a(0) = 1; a(n) = Sum_{k=1..n} (1 - 3^k) * binomial(n-1,k-1) * a(n-k).
%o A368017 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=sum(j=1, i, (1-3^j)*binomial(i-1, j-1)*v[i-j+1])); v;
%Y A368017 Cf. A355378.
%K A368017 sign
%O A368017 0,2
%A A368017 _Seiichi Manyama_, Dec 08 2023