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A255348 a(1)=1, a(2) = 2; for n > 2, a(n) is the smallest number not already used such that the set of prime divisors of one of the numbers {a(n-1), a(n)} is a subset of the set of prime divisors of the other. 2

%I

%S 1,2,4,6,3,9,12,8,10,5,15,25,20,16,14,7,21,27,18,24,30,32,22,11,33,66,

%T 36,42,28,49,35,70,40,50,60,45,75,81,39,13,26,52,64,34,17,51,102,48,

%U 54,72,78,96,84,56,98,112,126,63,105,125,55,110,44,88,121,77

%N a(1)=1, a(2) = 2; for n > 2, a(n) is the smallest number not already used such that the set of prime divisors of one of the numbers {a(n-1), a(n)} is a subset of the set of prime divisors of the other.

%C The sequence is an analog of EKG-sequence A064413 with more hard condition on neighbor terms. However, we conjecture that, as A064413, it is a permutation of the positive integers.

%C By the definition, every two neighbor terms are strictly connected numbers defined in comment in A257112.

%H Peter J. C. Moses, <a href="/A255348/b255348.txt">Table of n, a(n) for n = 1..5000</a>

%Y Cf. A064413, A257112.

%K nonn

%O 1,2

%A _Vladimir Shevelev_, May 05 2015

%E More terms from _Peter J. C. Moses_, May 05 2015

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Last modified January 27 01:45 EST 2021. Contains 340443 sequences. (Running on oeis4.)