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 A355070 #17 Jun 18 2022 13:59:44
%S A355070 0,1,-2,28,-1808,469072,-456745472,1601325615808,-19650153075181568,
%T A355070 826737899840505194752,-117393483573257494026125312,
%U A355070 55564698792825562646890851908608,-86789641569440259960965030826164092928
%N A355070 G.f.: Sum_{n>=0} a(n)*x^n/(n!*3^(n*(n-1)/2)) = log( Sum_{n>=0} x^n/(n!*3^(n*(n-1)/2)) ).
%F A355070 a(0) = 0; a(n) = 1 - Sum_{k=1..n-1} 3^(k*(n-k)) * binomial(n-1,k) * a(n-k).
%o A355070 (PARI) a(n) = n!*3^(n*(n-1)/2)*polcoef(log(sum(k=0, n, x^k/(k!*3^(k*(k-1)/2)))+x*O(x^n)), n);
%o A355070 (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, 3^(j*(i-j))*binomial(i-1, j)*v[i-j+1])); v;
%Y A355070 Cf. A134531, A355071.
%Y A355070 Cf. A188457, A355073.
%K A355070 sign
%O A355070 0,3
%A A355070 _Seiichi Manyama_, Jun 18 2022