A057723 - OEIS

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A057723

Sum of positive divisors of n that are divisible by every prime that divides n.

1, 2, 3, 6, 5, 6, 7, 14, 12, 10, 11, 18, 13, 14, 15, 30, 17, 24, 19, 30, 21, 22, 23, 42, 30, 26, 39, 42, 29, 30, 31, 62, 33, 34, 35, 72, 37, 38, 39, 70, 41, 42, 43, 66, 60, 46, 47, 90, 56, 60, 51, 78, 53, 78, 55, 98, 57, 58, 59, 90, 61, 62, 84, 126, 65, 66, 67, 102, 69, 70 (list; graph; refs; listen; history; internal format)

	OFFSET	`1,2`
	FORMULA	`If n = Product p_i^e_i then a(n) = Product (p_i + p_i^2 + ... + p_i^e_i).`
	EXAMPLE	`The divisors of 12 that are divisible by both 2 and 3 are 6 and 12. So a(12) = 6 + 12 = 18.`
	CROSSREFS	`Cf. A000203, A049060, A060640.` `Sequence in context: A118738 A175067 A051377 * A142151 A003968 A076734` `Adjacent sequences: A057720 A057721 A057722 * A057724 A057725 A057726`
	KEYWORD	`nonn,mult`
	AUTHOR	`Leroy Quet Oct 27 2000`

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Last modified February 15 21:56 EST 2012. Contains 205860 sequences.