A128556 a(1)=1. a(n) = the smallest positive multiple of d(a(n-1)) that does not occur earlier in the sequence, where d(m) is the number of positive divisors of m.

1, 2, 4, 3, 6, 8, 12, 18, 24, 16, 5, 10, 20, 30, 32, 36, 9, 15, 28, 42, 40, 48, 50, 54, 56, 64, 7, 14, 44, 60, 72, 84, 96, 108, 120, 80, 70, 88, 104, 112, 90, 132, 144, 45, 66, 128, 136, 152, 160, 156, 168, 176, 100, 27, 52, 78, 184, 192, 98, 102, 200, 180

Offset: 1

Author

Leroy Quet, Mar 10 2007

Keywords

• nonn

Comments

Is this sequence is a permutation of the positive integers?

Examples

			a(9) = 24 has 8 positive divisors. So a(10) is the smallest positive multiple of 8 that has yet to appear in the sequence. 8 occurs among the first 9 terms of the sequence, but 16 does not. So a(10) = 16.
		

Links

• Diana Mecum, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A128555.

Extensions

More terms from Diana L. Mecum, May 29 2007