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 A027119 #7 Oct 23 2019 20:33:29 %S A027119 1,4,9,23,59,154,407,1088,2935,7980,21843,60139,166425,462638,1291245, %T A027119 3616923,10164335,28648092,80960915,229360649,651237509,1852936294, %U A027119 5282196109,15084862158,43150636493,123624304356,354689105733 %N A027119 a(n) = A027113(n, 2n-1). %K A027119 nonn %O A027119 1,2 %A A027119 _Clark Kimberling_