id:A069926 - OEIS Search Results

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Number of k, 1<=k<=n, such that k divides sigma(k).

+0
1

1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 (list; graph; listen)

	OFFSET	`1,6`
	FORMULA	`a(n)=Card(k: 1<=k<=n : sigma(k) == 0 (mod k) ) : asymptotically a(n)=C*ln(n)+o(ln(n)) with C=0, 7...`
	PROGRAM	`(PARI) for(n=1, 150, print1(sum(i=1, n, if(sigma(i)%(i), 0, 1)), ", "))`
	CROSSREFS	`Sequence in context: A111892 A108248 A087104 this_sequence A077429 A060417 A097944` `Adjacent sequences: A069923 A069924 A069925 this_sequence A069927 A069928 A069929`
	KEYWORD	`easy,nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), May 05 2002`

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Last modified November 21 14:49 EST 2008. Contains 150807 sequences.

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