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 A181981 #26 Feb 21 2023 09:55:04 %S A181981 3,17,41,107,71,2267,1091,461,1319,1151,347,5741,2999,5279,10139,1487, %T A181981 9461,881,659,13007,9041,15359,8627,28751,83717,13397,18539,14627, %U A181981 44771,54011,60257,59669,142157,77711,61559,178931,26261,122867,293261,89069,24419 %N A181981 Duplicate of A089637. %K A181981 dead %O A181981 0,1