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 A131831 #36 Jun 02 2025 00:31:56 %S A131831 1,4,8,14,24,42,76,142,272,530,1044,2070,4120,8218,16412,32798,65568, %T A131831 131106,262180,524326,1048616,2097194,4194348,8388654,16777264, %U A131831 33554482,67108916 %N A131831 Duplicate of A100314. %K A131831 dead %O A131831 0,2