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 A024977 #13 Aug 05 2019 19:36:08 %S A024977 1,3,5,7,8,10,12,15,17,19,20,22,24,26,28,31,32,34,37,38,41,43,44,47, %T A024977 48,51,52,53,55,58,59,62,63,65,67,68,70,73,75,77,80,82,83,87,88,91,92, %U A024977 93,95,97,100,101,102,105,107,108,111,113,116,117,118,121,123,125,126,128,129,133,135 %N A024977 Positions of even numbers in A024975. %K A024977 nonn %O A024977 1,2 %A A024977 _Clark Kimberling_