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

1,2

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.

Sequence in context: A357963 A357994 A357942 * A342366 A336946 A357777

Adjacent sequences: A255345 A255346 A255347 * A255349 A255350 A255351

Keyword

nonn

Author

Vladimir Shevelev, May 05 2015

Extensions

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

Status

approved