id:A013939 - OEIS Search Results

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Partial sums of sequence A001221 (number of distinct primes dividing n).

+0
19

0, 1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 14, 15, 17, 19, 20, 21, 23, 24, 26, 28, 30, 31, 33, 34, 36, 37, 39, 40, 43, 44, 45, 47, 49, 51, 53, 54, 56, 58, 60, 61, 64, 65, 67, 69, 71, 72, 74, 75, 77, 79, 81, 82, 84, 86, 88, 90, 92, 93, 96, 97, 99, 101, 102, 104, 107, 108, 110, 112 (list; graph; listen)

	OFFSET	`1,3`
	COMMENT	`a(n) = A093614(n) - A048865(n); see also A006218.`
	LINKS	`Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.`
	FORMULA	`a(n) = Sum{ k <= n} omega(k).` `a(n) = Sum_{ k = 1 .. n} floor( n/prime(k) ).` `a(n) =a(n-1)+A001221(n)` `a(n) = Sum_{k=1..n} pi(floor(n/k)). - Vladeta Jovovic (vladeta(AT)eunet.rs), Jun 18 2006`
	CROSSREFS	`Cf. A005187, A006218, A011371, A013936 for similar entries.` `A027748(a(A000040(n))+1) = A000040(n), A082287(a(n)+1) = n.` `Sequence in context: A008320 A004439 A050126 this_sequence A004144 A124391 A050118` `Adjacent sequences: A013936 A013937 A013938 this_sequence A013940 A013941 A013942`
	KEYWORD	`nonn,easy,nice`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com), Henri Lifchitz (100637.64(AT)CompuServe.COM)`
	EXTENSIONS	`More terms from Henry Bottomley (se16(AT)btinternet.com), Jul 03 2001`

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.

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