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 A367838 #8 Dec 02 2023 08:12:59
%S A367838 1,1,6,38,344,3832,51408,803952,14371456,289005440,6457624832,
%T A367838 158719896832,4255775425536,123619815742464,3867071262472192,
%U A367838 129610289219999744,4633674344869756928,176011269522607144960,7079115958438736363520
%N A367838 Expansion of e.g.f. 1/(2 + x - exp(2*x)).
%F A367838 a(0) = 1; a(n) = -n * a(n-1) + Sum_{k=1..n} 2^k * binomial(n,k) * a(n-k).
%o A367838 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=-i*v[i]+sum(j=1, i, 2^j*binomial(i, j)*v[i-j+1])); v;
%Y A367838 Cf. A032032, A367839, A367840.
%Y A367838 Cf. A367835.
%K A367838 nonn
%O A367838 0,3
%A A367838 _Seiichi Manyama_, Dec 02 2023