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 A027142 #8 Oct 23 2019 22:07:45
%S A027142 12,105,831,6648,53545,434458,3548871,29166324,241006333,2001145585,
%T A027142 16688238416,139711675493,1173762075101,9892582661593,83617537623039,
%U A027142 708654873428000,6020421349942965,51261344063828713,437370998284452284,3738875265960650016
%N A027142 a(n) = Sum_{k=0..2n-2} T(n,k) * T(n,k+2), with T given by A027113.
%K A027142 nonn
%O A027142 2,1
%A A027142 _Clark Kimberling_
%E A027142 More terms from _Sean A. Irvine_, Oct 23 2019