id:A069248 - OEIS Search Results

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Number of positive divisors of n themselves divisible by largest prime that divides n.

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1

0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 4, 1, 3, 2, 2, 1, 4, 2, 2, 3, 3, 1, 4, 1, 5, 2, 2, 2, 6, 1, 2, 2, 4, 1, 4, 1, 3, 3, 2, 1, 5, 2, 4, 2, 3, 1, 6, 2, 4, 2, 2, 1, 6, 1, 2, 3, 6, 2, 4, 1, 3, 2, 4, 1, 8, 1, 2, 4, 3, 2, 4, 1, 5, 4, 2, 1, 6, 2, 2, 2, 4, 1, 6, 2, 3, 2, 2, 2, 6, 1, 4, 3, 6 (list; graph; listen)

	OFFSET	`1,4`
	FORMULA	`d(n) E_n/(E_n + 1), where d(n) is the number of positive divisors of n, and E_n is the exponent of the largest prime to divide n in the prime factorization of n.`
	EXAMPLE	`The divisors of 12 which are themselves divisible by 3 (the largest prime dividing 12) are 3, 6, and 12. So the 12th term is 3.`
	CROSSREFS	`Sequence in context: A086436 A001222 A098893 this_sequence A008481 A127669 A056692` `Adjacent sequences: A069245 A069246 A069247 this_sequence A069249 A069250 A069251`
	KEYWORD	`nonn`
	AUTHOR	`Leroy Quet (qq-quet(AT)mindspring.com), Apr 08 2002`

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Last modified September 6 16:04 EDT 2008. Contains 143483 sequences.

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