id:A069184 - OEIS Search Results

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Sum of divisors d of n such that d or n/d is odd.

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4

1, 3, 4, 5, 6, 12, 8, 9, 13, 18, 12, 20, 14, 24, 24, 17, 18, 39, 20, 30, 32, 36, 24, 36, 31, 42, 40, 40, 30, 72, 32, 33, 48, 54, 48, 65, 38, 60, 56, 54, 42, 96, 44, 60, 78, 72, 48, 68, 57, 93, 72, 70, 54, 120, 72, 72, 80, 90, 60, 120, 62, 96, 104, 65, 84, 144, 68, 90, 96 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Might be called UnitaryOrdinarySigma(n): If n=Product p_i^r_i then UOSigma(n)=UnitarySigma(2^r_1)Sigma(n/2^r_1)=(2^r_1+1)Product (p_i^(r_i+1)-1)/(p_i-1), p_i is not 2. - Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), Jun 11 2005`
	FORMULA	`Multiplicative with a(2^e) = 2^e+1 and a(p^e) = (p^(e+1)-1)/(p-1) for an odd prime p.` `G.f.: Sum_{m>0} mx^m(1+x^m+x^(2m)-x^(3m))/(1-x^(4*m)).`
	EXAMPLE	`UOSigma(2^47^2)=UnitarySigma(2^4)sigma(7^2)=17*57=969`
	CROSSREFS	`Cf. A069733, A107749, A092356.` `Adjacent sequences: A069181 A069182 A069183 this_sequence A069185 A069186 A069187` `Sequence in context: A048989 A103402 A034448 this_sequence A049417 A125139 A107224`
	KEYWORD	`mult,nonn`
	AUTHOR	`Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 10 2002`
	EXTENSIONS	`Edited by njas, Aug 29 2008 at the suggestion of R. J. Mathar`

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Last modified October 13 20:18 EDT 2008. Contains 145016 sequences.

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