id:A080224 - OEIS Search Results

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Number of abundant divisors of n.

+0
8

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 5, 0, 0, 0, 0, 0, 1, 0, 3, 0, 0, 0, 3, 0, 0, 0, 1, 0, 3, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 0, 1, 0, 1, 0 (list; graph; listen)

	OFFSET	`1,24`
	COMMENT	`Number of divisors d of n with sigma(d)>2*d (sigma=A000203); a(n)+A080225(n)+A080226(n)=A000005(n).` `a(n)>0 iff n is abundant: a(A005101(n))>0, a(A000396(n))=0 and a(A005100(n))=0; a(A091191(n))=1; a(A091192(n))>1; a(A091193(n))=n and a(m)<>n for m<A091193(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Dec 27 2003`
	LINKS	`Eric Weisstein's World of Mathematics, Abundant Number.`
	EXAMPLE	`Divisors of n=24: {1,2,3,4,6,8,12,24}, two of them are abundant: 12=A005101(1) and 24=A005101(4), therefore a(24)=2.`
	CROSSREFS	`Cf. A005101, A000203.` `Sequence in context: A122841 A060862 A066087 this_sequence A010105 A083916 A083893` `Adjacent sequences: A080221 A080222 A080223 this_sequence A080225 A080226 A080227`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 07 2003`

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Last modified December 5 23:38 EST 2009. Contains 170428 sequences.

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