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 A361847 #13 Apr 07 2023 02:33:19
%S A361847 1,3,12,27,-75,-444,4734,11532,-466782,1626750,50347410,-708889296,
%T A361847 -2196754992,179878246239,-1795732735128,-24691325878980,
%U A361847 953903679982809,-7684914725016600,-226465559200630566,7742131606464606525,-58889021552013912990
%N A361847 a(n) = (-1)^n * Sum_{k=0..n} 9^k * binomial(-1/3,k) * binomial(n*k,n-k).
%H A361847 Winston de Greef, <a href="/A361847/b361847.txt">Table of n, a(n) for n = 0..468</a>
%F A361847 a(n) = [x^n] 1/(1 - 9*x*(1-x)^n)^(1/3).
%o A361847 (PARI) a(n) = (-1)^n*sum(k=0, n, 9^k*binomial(-1/3, k)*binomial(n*k, n-k));
%Y A361847 Main diagonal of A361840.
%Y A361847 Cf. A361835, A361846.
%K A361847 sign
%O A361847 0,2
%A A361847 _Seiichi Manyama_, Mar 27 2023