id:A074753 - OEIS Search Results

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Number of integers k such that sigma(k) < n.

+0
1

0, 1, 1, 2, 3, 3, 4, 5, 6, 6, 6, 6, 8, 9, 10, 11, 11, 11, 13, 13, 14, 14, 14, 14, 17, 17, 17, 17, 18, 18, 19, 21, 23, 23, 23, 23, 24, 24, 25, 26, 27, 27, 30, 30, 31, 31, 31, 31, 34, 34, 34, 34, 34, 34, 36, 36, 38, 39, 39, 39, 42, 42, 43, 44, 44, 44, 44, 44, 45, 45, 45, 45, 50, 50 (list; graph; listen)

	OFFSET	`1,4`
	FORMULA	`a(n) = card( k : sigma(k) < n ); a(n) is asymptotic to c*n with c=0.67...`
	PROGRAM	`(PARI) a(n)=sum(i=1, n, if(1+sign(sigma(i)-n), 0, 1))`
	CROSSREFS	`Sequence in context: A157222 A064047 A111899 this_sequence A013928 A006161 A132351` `Adjacent sequences: A074750 A074751 A074752 this_sequence A074754 A074755 A074756`
	KEYWORD	`nonn`
	AUTHOR	`Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 28 2002`

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Last modified November 25 14:49 EST 2009. Contains 167514 sequences.

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