The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A005087 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A005087

Number of distinct odd primes dividing n.
(history; published version)

#45 by Michel Marcus at Thu Sep 28 04:22:32 EDT 2023

STATUS

reviewed

approved

#44 by Joerg Arndt at Thu Sep 28 01:58:27 EDT 2023

STATUS

proposed

reviewed

#43 by Amiram Eldar at Thu Sep 28 01:43:12 EDT 2023

STATUS

editing

proposed

#42 by Amiram Eldar at Thu Sep 28 01:26:47 EDT 2023

FORMULA

Sum_{k=1..n} a(k) = n * log(log(n)) + c * n + O(n/log(n)), where c = A077761 - 1/2 = - 0.238502... . - Amiram Eldar, Sep 28 2023

#41 by Amiram Eldar at Thu Sep 28 01:25:51 EDT 2023

AUTHOR

N. J. A. Sloane.

#40 by Amiram Eldar at Thu Sep 28 01:25:42 EDT 2023

FORMULA

Sum_{k=1..n} a(k) = n * log(log(n)) + c * n + O(n/log(n)), where c = A077761 - 1/2 = - 0.238502... . - Amiram Eldar, Sep 28 2023

CROSSREFS

Cf. A001221, A077761, A087436.

STATUS

approved

editing

#39 by Michael De Vlieger at Mon Sep 18 09:01:14 EDT 2023

STATUS

reviewed

approved

#38 by Joerg Arndt at Mon Sep 18 07:40:06 EDT 2023

STATUS

proposed

reviewed

#37 by Amiram Eldar at Mon Sep 18 06:54:45 EDT 2023

STATUS

editing

proposed

#36 by Amiram Eldar at Mon Sep 18 06:54:42 EDT 2023

COMMENTS

a(n) = A001221(n) - 1 + n mod 2. - Reinhard Zumkeller, Sep 03 2003

FORMULA

a(n) = A001221(n) - 1 + n mod 2. - Reinhard Zumkeller, Sep 03 2003

CROSSREFS

Cf. A001221, A087436.

KEYWORD

nonn,easy,changed

STATUS

proposed

editing