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 A121515 #29 Sep 04 2020 10:25:48 %S A121515 3,33,315,26163,235953,2125035,19129689,172180323,1549662273, %T A121515 13947078555,125524061289,1129717614483,10167461718993,91507165036875, %U A121515 823564514029689,7412080712360643,66708726669526113,600378540800575995,5403406869529706889,48630661832740930803 %N A121515 Incorrect duplicate of A226508. %C A121515 The term 2889 is missing. %K A121515 dead %O A121515 1,1 %A A121515 _Jonathan Vos Post_, Sep 07 2006