id:A072697 - OEIS Search Results

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Square-free numbers such that the sum of the prime factors is a multiple of the number of prime factors.

+0
5

2, 3, 5, 7, 11, 13, 15, 17, 19, 21, 23, 29, 31, 33, 35, 37, 39, 41, 42, 43, 47, 51, 53, 55, 57, 59, 61, 65, 67, 69, 71, 73, 77, 78, 79, 83, 85, 87, 89, 91, 93, 95, 97, 101, 103, 105, 107, 109, 110, 111, 113, 114, 115, 119, 123, 127, 129, 131, 133, 137, 139, 141, 143 (list; graph; listen)

	OFFSET	`1,1`
	EXAMPLE	`42=237: number of factors = 3 and sum of factors =2+3+7=12, as 12=4*3, 42 is a term: a(19)=42, A072698(19)=3, A072699(19)=12 and A072700(19)=4 contributes 1 count for A072701(4), as (2+3+7)/3=4.`
	CROSSREFS	`Cf. A005117, A072700, A072701, A072698, A072699.` `Sequence in context: A097312 A095179 A074895 this_sequence A090421 A102553 A069161` `Adjacent sequences: A072694 A072695 A072696 this_sequence A072698 A072699 A072700`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jul 04 2002`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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