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Inverse permutation to A355212.
2

%I #8 Jun 26 2022 09:15:22

%S 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 36,38,40,42,35,44,46,15,23,9,37,48,50,19,51,53,39,55,57,59,31,61,58,

%U 63,65,67,69,71,66,73,64,27,41,75,68,77,45,79,81,83,80,85

%N Inverse permutation to A355212.

%C 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 Rémy Sigrist, <a href="/A355213/b355213.txt">Table of n, a(n) for n = 1..10000</a>

%H Rémy Sigrist, <a href="/A355213/a355213.gp.txt">PARI program</a>

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%e A355212(39) = 42 so a(42) = 39.

%o (PARI) See Links section.

%Y Cf. A355212.

%K nonn

%O 1,2

%A _Rémy Sigrist_, Jun 24 2022