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 A027224 #9 Oct 25 2019 04:57:50
%S A027224 1,6,24,132,500,2728,10324,56651,215323,1191987,4549786,25420734,
%T A027224 97369588,548884043,2108335364,11983465575,46136052623,264215445322,
%U A027224 1019173758683,5876647410170,22705355331214,131727633042981,509673506069905,2973264727753047,11518483809430525
%N A027224 a(n) = Sum_{k=0..n-1} T(n,k) * T(n,k+1), with T given by A026747.
%K A027224 nonn
%O A027224 1,2
%A A027224 _Clark Kimberling_
%E A027224 More terms from _Sean A. Irvine_, Oct 24 2019