id:A128556 - OEIS Search Results

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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.

+0
2

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 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Is this sequence is a permutation of the positive integers?`
	LINKS	`Diana Mecum, Table of n, a(n) for n = 1..1000`
	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: A128555 A039874 A114107 this_sequence A077661 A139413 A077583` `Adjacent sequences: A128553 A128554 A128555 this_sequence A128557 A128558 A128559`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Mar 10 2007`
	EXTENSIONS	`More terms from Diana Mecum (diana.mecum(AT)gmail.com), May 29 2007`

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.

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