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 A352571 #10 Apr 05 2022 17:06:50 %S A352571 1,-1,2,-1,13,3,17,-1,5,8,25,4,9,14,45,-1,6,7,21,10,24,28,50,15,20,40, %T A352571 34,31,41,35,80,-1,12,22,68,23,42,55,63,26,30,56,64,51,75,86,125,11, %U A352571 16,72,95,27,46,59,99,60,69,91,124,87,139,168,249,-1,33,18,29,32,58,71,103,19,57,44,112,70,108,90,117,47,53,94,145,66,83,76,149,65 %N A352571 Index of n in A338833, or -1 if n does not appear there. %C A352571 a(n) = -1 iff n = 2^k, k>0. %H A352571 Rémy Sigrist, <a href="/A352571/b352571.txt">Table of n, a(n) for n = 1..10000</a> %H A352571 Rémy Sigrist, <a href="/A352571/a352571.gp.txt">PARI program</a> %o A352571 (PARI) See Links section. %Y A352571 Cf. A338833, A352572. %K A352571 sign %O A352571 1,3 %A A352571 _N. J. A. Sloane_, Apr 04 2022