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 A355071 #13 Jun 18 2022 13:59:55
%S A355071 0,1,-3,81,-13311,11688705,-51334027263,1082183686000641,
%T A355071 -106464672910860746751,47880898685034024043741185,
%U A355071 -96901748928702482338511172665343,871602415363671863767026450797790494721
%N A355071 G.f.: Sum_{n>=0} a(n)*x^n/(n!*4^(n*(n-1)/2)) = log( Sum_{n>=0} x^n/(n!*4^(n*(n-1)/2)) ).
%F A355071 a(0) = 0; a(n) = 1 - Sum_{k=1..n-1} 4^(k*(n-k)) * binomial(n-1,k) * a(n-k).
%o A355071 (PARI) a(n) = n!*4^(n*(n-1)/2)*polcoef(log(sum(k=0, n, x^k/(k!*4^(k*(k-1)/2)))+x*O(x^n)), n);
%o A355071 (PARI) a_vector(n) = my(v=vector(n+1)); v[1]=0; for(i=1, n, v[i+1]=1-sum(j=1, i-1, 4^(j*(i-j))*binomial(i-1, j)*v[i-j+1])); v;
%Y A355071 Cf. A134531, A355070.
%Y A355071 Cf. A137435, A355074.
%K A355071 sign
%O A355071 0,3
%A A355071 _Seiichi Manyama_, Jun 18 2022