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 A117253 #6 Mar 15 2023 14:17:48
%S A117253 1,1,-3,45,-2430,433026,-245525742,434685788658,-2376644549487615,
%T A117253 39849199161258840705,-2039314646436750180150939,
%U A117253 317469566015078743658568283029,-149970083228995077874358388356635368,214577598849654850870918566871719460091160
%N A117253 Column 0 of triangle A117252.
%F A117253 a(n) = [Product_{j=0..n-1} (1-3*j)]/n! * 3^(n*(n-1)/2).
%o A117253 (PARI) a(n)=prod(j=0,n-1,1-3*j)/n!*3^(n*(n-1)/2)
%Y A117253 Cf. A117252.
%K A117253 sign
%O A117253 0,3
%A A117253 _Paul D. Hanna_, Mar 14 2006