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 A291091 #7 Aug 20 2017 12:38:38 %S A291091 1,2,7,28,122,562,2693,13288,67064,344588,1796518,9479780,50532640, %T A291091 271710662,1471935235,8026070768,44015873308,242619318848, %U A291091 1343427572648,7469219870968,41680871386016,233373274580372,1310659959443722,7381448319246248,41678055955034962 %N A291091 a(n) = A214938(2n+1). %H A291091 Lars Blomberg, <a href="/A291091/b291091.txt">Table of n, a(n) for n = 0..1000</a> %Y A291091 Cf. A214938, A291090. %K A291091 nonn %O A291091 0,2 %A A291091 _N. J. A. Sloane_, Aug 19 2017 %E A291091 a(17)-a(24) from _Lars Blomberg_, Aug 20 2017