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 A144921 #13 Jul 21 2020 09:45:54 %S A144921 7,13,19,31,37,43,61,67,73,79,97,103,109,127,139,151,157,163,181,193, %T A144921 199,211,223,229,241,271,277,283,307,313,331,337,349,367,373,379,397, %U A144921 409,421,433,439,457,463,487,499,523,541,547,571,577,601,607,613,619 %N A144921 Duplicate of A002476. %K A144921 dead %O A144921 1,1