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 A144272 #6 Jul 02 2023 06:07:25 %S A144272 1,1,4,18,129,1095,11880,149940,2218545,37147005,699281100, %T A144272 14561835750,332913128625,8280095098275,222659485448400, %U A144272 6434896997529000,198909798356894625,6547761582390653625,228681849947367316500,8445341134525197152250,328822530412023653630625 %N A144272 Second column (m=2) of triangle S2hat(-1) = A144270. %F A144272 a(n) = A144270(n+2,2), n>=0. %Y A144272 Cf. A144270. %Y A144272 Cf. A001147 (column m=1), A144273 (column m=3). %K A144272 nonn,easy %O A144272 0,3 %A A144272 _Wolfdieter Lang_, Oct 09 2008