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 A027240 #8 Oct 26 2019 15:27:19
%S A027240 1,4,19,80,391,1738,8797,40878,212491,1023392,5426518,26891674,
%T A027240 144717381,733600690,3991767587,20603079346,113049604075,591971513924,
%U A027240 3269119157724,17319091807608,96127613360983,514139933872914,2865265217457906,15446276427044382,86367699910234830
%N A027240 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026769.
%K A027240 nonn
%O A027240 1,2
%A A027240 _Clark Kimberling_
%E A027240 More terms from _Sean A. Irvine_, Oct 26 2019