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 A351793 #11 Feb 19 2022 10:04:17 %S A351793 1,1,-6,6,248,-2120,-12144,458416,-2194560,-102238848,2116494080, %T A351793 12999644416,-1291721856000,14270887521280,650218659514368, %U A351793 -24515781088389120,-89087389799317504,27917287109308284928,-556978307357438705664,-23150337968775391281152 %N A351793 Expansion of e.g.f. 1/(1 - x*exp(-4*x)). %F A351793 a(n) = n! * Sum_{k=0..n} (-4 * (n-k))^k/k!. %F A351793 a(0) = 1 and a(n) = n * Sum_{k=0..n-1} (-4)^(n-1-k) * binomial(n-1,k) * a(k) for n > 0. %t A351793 a[0] = 1; a[n_] := n!*Sum[(-4*(n - k))^k/k!, {k, 0, n}]; Array[a, 20, 0] (* _Amiram Eldar_, Feb 19 2022 *) %o A351793 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(1/(1-x*exp(-4*x)))) %o A351793 (PARI) a(n) = n!*sum(k=0, n, (-4*(n-k))^k/k!); %o A351793 (PARI) a(n) = if(n==0, 1, n*sum(k=0, n-1, (-4)^(n-1-k)*binomial(n-1, k)*a(k))); %Y A351793 Column k=4 of A351791. %Y A351793 Cf. A336952. %K A351793 sign %O A351793 0,3 %A A351793 _Seiichi Manyama_, Feb 19 2022