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 A355213 #8 Jun 26 2022 09:15:22 %S A355213 1,2,4,6,8,3,10,12,14,7,16,5,18,11,20,22,24,13,26,21,28,30,32,29,34, %T A355213 36,38,40,42,35,44,46,15,23,9,37,48,50,19,51,53,39,55,57,59,31,61,58, %U A355213 63,65,67,69,71,66,73,64,27,41,75,68,77,45,79,81,83,80,85 %N A355213 Inverse permutation to A355212. %C A355213 Equivalently: lexicographically earliest sequence of distinct positive integers such that a(1) = 1, and for any m, n > 1, if abs(a(n) - a(m)) = 1, then gcd(m, n) > 1. %H A355213 Rémy Sigrist, <a href="/A355213/b355213.txt">Table of n, a(n) for n = 1..10000</a> %H A355213 Rémy Sigrist, <a href="/A355213/a355213.gp.txt">PARI program</a> %H A355213 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a> %e A355213 A355212(39) = 42 so a(42) = 39. %o A355213 (PARI) See Links section. %Y A355213 Cf. A355212. %K A355213 nonn %O A355213 1,2 %A A355213 _Rémy Sigrist_, Jun 24 2022