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 A047770 #11 Mar 31 2024 17:13:53 %S A047770 0,1,5,26,133,708,3860,21604,123266,715216,4206956,25032840,150413322, %T A047770 911379384,5562367173,34164355715,211015212580,1309815397995, %U A047770 8166460799097,51120054233490,321156223592865,2024257417808379,12797201858645100,81125118975874896,515573991508620164,3284258706735132028 %N A047770 a(n) = A047769(2n). %K A047770 nonn %O A047770 1,3 %A A047770 _N. J. A. Sloane_