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 A027137 #8 Oct 23 2019 22:10:16
%S A027137 1,9,40,163,606,2149,7378,24767,81784,266721,861426,2760523,8790108,
%T A027137 27841469,87789916,275762167,863353934,2695201705,8392538682,
%U A027137 26074810851,80850124228,250242934405,773288315888,2386084417999
%N A027137 a(n) = Sum_{k=0..2n} (k+1) * A027113(n, k).
%K A027137 nonn
%O A027137 0,2
%A A027137 _Clark Kimberling_