id:A080226 - OEIS Search Results

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Number of deficient divisors of n.

+0
3

1, 2, 2, 3, 2, 3, 2, 4, 3, 4, 2, 4, 2, 4, 4, 5, 2, 4, 2, 5, 4, 4, 2, 5, 3, 4, 4, 5, 2, 6, 2, 6, 4, 4, 4, 5, 2, 4, 4, 6, 2, 6, 2, 6, 6, 4, 2, 6, 3, 6, 4, 6, 2, 5, 4, 6, 4, 4, 2, 7, 2, 4, 6, 7, 4, 6, 2, 6, 4, 7, 2, 6, 2, 4, 6, 6, 4, 6, 2, 7, 5, 4, 2, 7, 4, 4, 4, 7, 2, 8, 4, 6, 4, 4, 4, 7, 2, 6, 6, 7, 2, 6, 2, 7, 8 (list; graph; listen)

	OFFSET	`1,2`
	COMMENT	`Number of divisors d of n with sigma(d)<2*d (sigma=A000203); A080224(n)+A080225(n)+a(n)=A000005(n).`
	LINKS	`Eric Weisstein's World of Mathematics, Deficient Number.`
	EXAMPLE	`All 4 divisors of n=21 are deficient: 1=A005100(1), 3=A005100(3), 7=A005100(6) and 21=A005100(17), therefore a(21)=4.`
	CROSSREFS	`Cf. A005100, A000203.` `Sequence in context: A135981 A135615 A166469 this_sequence A060741 A125747 A060129` `Adjacent sequences: A080223 A080224 A080225 this_sequence A080227 A080228 A080229`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 07 2003`

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Last modified December 19 12:50 EST 2009. Contains 171053 sequences.

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