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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.
3
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
1,2
COMMENTS
Is this sequence is a permutation of the positive integers?
EXAMPLE
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.
CROSSREFS
Cf. A128555.
Sequence in context: A114107 A362041 A175334 * A212485 A077661 A077583
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 10 2007
EXTENSIONS
More terms from Diana L. Mecum, May 29 2007
STATUS
approved