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.

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, 36, 42, 28, 49, 35, 70, 40, 50, 60, 45, 75, 81, 39, 13, 26, 52, 64, 34, 17, 51, 102, 48, 54, 72, 78, 96, 84, 56, 98, 112, 126, 63, 105, 125, 55, 110, 44, 88, 121, 77

Offset: 1

Author

Vladimir Shevelev, May 05 2015

Keywords

• nonn

Comments

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.

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

Links

• Peter J. C. Moses, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A064413, A257112.

Extensions

More terms from Peter J. C. Moses, May 05 2015