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 A027127 #7 Oct 23 2019 22:10:27 %S A027127 1,4,13,44,149,504,1701,5715,19079,63218,207803,677598,2192383, %T A027127 7041688,22463815,71216406,224495351,704036264,2197641219,6831066997, %U A027127 21152812449,65276358340,200814955029,616052453764,1885109044861 %N A027127 a(n) = A027113(n, 2n-9). %K A027127 nonn %O A027127 5,2 %A A027127 _Clark Kimberling_