id:A070982 - OEIS Search Results

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Smallest integer k such that n divides sigma(k).

+0
3

1, 3, 2, 3, 8, 5, 4, 7, 10, 19, 43, 6, 9, 12, 8, 21, 67, 10, 37, 19, 20, 43, 137, 14, 149, 45, 34, 12, 173, 24, 16, 21, 86, 67, 76, 22, 73, 37, 18, 27, 163, 20, 257, 43, 40, 137, 281, 33, 52, 149, 101, 63, 211, 34, 109, 28, 49, 173, 353, 24, 169, 48, 32, 93, 72, 86, 401 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n) = min( k : sigma(k) == 0 mod(n) )` `Sum(k=1, n, a(k)) seems to be asymptotic to c*n^2 with probably 1.1 < c < 1.2`
	PROGRAM	`(PARI) a(n)=if(n<0, 0, s=1; while(sigma(s)%n>0, s++); s)`
	CROSSREFS	`Sequence in context: A141863 A071010 A073341 this_sequence A123649 A080848 A016602` `Adjacent sequences: A070979 A070980 A070981 this_sequence A070983 A070984 A070985`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 24 2002`

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Last modified December 17 23:40 EST 2009. Contains 171025 sequences.

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