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 A347691 #7 Sep 26 2021 23:21:15 %S A347691 20,1,11,10,8,3,38,5,17,4,6,19,9,16,24,14,21,27,12,2,25,36,28,15,32, %T A347691 43,18,23,74,33,37,39,42,29,44,22,31,46,45,56,47,52,26,48,61,60,41,49, %U A347691 53,73,59,13,57,91,64,40,66,62,51,7,30,58,101,55,70,69,86,34,75,65,80,78,50 %N A347691 a(n) = index of n in A308387, or -1 if n does not appear in A308387. %H A347691 N. J. A. Sloane, <a href="/A347691/b347691.txt">Table of n, a(n) for n = 1..6867</a> %e A347691 A308387(20) = 1, so a(1) = 20. %Y A347691 Cf. A308387. %K A347691 nonn %O A347691 1,1 %A A347691 _N. J. A. Sloane_, Sep 26 2021