The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A056169 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A056169

Number of unitary prime divisors of n.
(history; published version)

#99 by Michel Marcus at Thu Sep 28 04:21:46 EDT 2023

STATUS

reviewed

approved

#98 by Joerg Arndt at Thu Sep 28 01:58:31 EDT 2023

STATUS

proposed

reviewed

#97 by Amiram Eldar at Thu Sep 28 01:43:16 EDT 2023

STATUS

editing

proposed

#96 by Amiram Eldar at Thu Sep 28 01:21:32 EDT 2023

KEYWORD

nonn,nice,easy,changed

#95 by Amiram Eldar at Thu Sep 28 01:21:21 EDT 2023

LINKS

Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CatalansConjecture.html">Catalan's Conjecture</a>.

<a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>.

FORMULA

Sum_{k=1..n} a(k) ~ n * (log(log(n)) + B - C), where B is Mertens's constant (A077761) and C = Sum_{p prime} (1/p^2) = 0.452247... (A085548). - Amiram Eldar, Sep 28 2023

CROSSREFS

Cf. A077761, A085548.

STATUS

approved

editing

#94 by Alois P. Heinz at Sat Apr 25 15:59:32 EDT 2020

STATUS

reviewed

approved

#93 by Michel Marcus at Sat Apr 25 15:03:27 EDT 2020

STATUS

proposed

reviewed

#92 by F. Chapoton at Sat Apr 25 14:47:59 EDT 2020

STATUS

editing

proposed

#91 by F. Chapoton at Sat Apr 25 14:47:52 EDT 2020

PROG

from sympy import factorint(n)

STATUS

proposed

editing

Discussion

Sat Apr 25

14:47

F. Chapoton: fixed

#90 by F. Chapoton at Sat Apr 25 12:39:35 EDT 2020

STATUS

editing

proposed

Discussion

Sat Apr 25

12:55

Michel Marcus: from sympy import factorint(n)  SyntaxError: invalid syntax