id:A046520 - OEIS Search Results

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Sum of divisors of n - phi(n) - number of divisors of n.

+0
3

-1, 0, 0, 2, 0, 6, 0, 7, 4, 10, 0, 18, 0, 14, 12, 18, 0, 27, 0, 28, 16, 22, 0, 44, 8, 26, 18, 38, 0, 56, 0, 41, 24, 34, 20, 70, 0, 38, 28, 66, 0, 76, 0, 58, 48, 46, 0, 98, 12, 67, 36, 68, 0, 94, 28, 88, 40, 58, 0, 140, 0, 62, 62, 88, 32, 116, 0, 88, 48, 112, 0, 159, 0, 74 (list; graph; listen)

	OFFSET	`1,4`
	COMMENT	`Always >= 0 for n >= 2. a(n)=0 if and only if n is prime.`
	REFERENCES	`D. S. Mitrinovic et al., Handbook of Number Theory, Kluwer, Section I.3.1 (but they have "tau" instead of "sigma").`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..10000` `N. J. A. Sloane, My favorite integer sequences, in Sequences and their Applications (Proceedings of SETA '98).`
	CROSSREFS	`Cf. A079538, A079539` `a(n) = A000203(n) - A000010(n) - A000005(n).` `Sequence in context: A050821 A076257 A162974 this_sequence A157195 A019781 A167294` `Adjacent sequences: A046517 A046518 A046519 this_sequence A046521 A046522 A046523`
	KEYWORD	`sign,easy`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com).`
	EXTENSIONS	`Corrected by Dean Hickerson, dean.hickerson(AT)yahoo.com, Dec 19 2006`

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Last modified November 25 14:49 EST 2009. Contains 167514 sequences.

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