id:A107758 - OEIS Search Results

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(+2)Sigma(n) : If n=Product p_i^r_i then (+2)Sigma(n)=Product (2+Sum p_i^s_i, s_i=1 to r_i)=Product(1+(p_i^(r_i+1)-1)/(p_i-1)), (+2)Sigma(1)=1.

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1, 4, 5, 8, 7, 20, 9, 16, 14, 28, 13, 40, 15, 36, 35, 32, 19, 56, 21, 56 (list; graph; listen)

	OFFSET	`1,2`
	EXAMPLE	`(+2)Sigma(6)=(2+2)*(2+3)=20.`
	CROSSREFS	`Cf. A107759, A052396.` `Sequence in context: A020804 A021222 A132023 this_sequence A104883 A154885 A042956` `Adjacent sequences: A107755 A107756 A107757 this_sequence A107759 A107760 A107761`
	KEYWORD	`nonn,mult`
	AUTHOR	`Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp), May 25 2005`

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Last modified December 8 08:31 EST 2009. Contains 170430 sequences.