The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A318874

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Showing entries 1-10 | older changes

A318874

Number of divisors d of n for which 2*phi(d) > d.
(history; published version)

#14 by Joerg Arndt at Mon Jul 08 10:40:54 EDT 2024

STATUS

reviewed

approved

#13 by Michel Marcus at Mon Jul 08 10:34:46 EDT 2024

STATUS

proposed

reviewed

#12 by Paolo Xausa at Mon Jul 08 09:33:59 EDT 2024

STATUS

editing

proposed

#11 by Paolo Xausa at Mon Jul 08 09:30:10 EDT 2024

MATHEMATICA

A318874[n_] := DivisorSum[n, 1 &, 2*EulerPhi[#] > # &];

Array[A318874, 100] (* Paolo Xausa, Jul 08 2024 *)

STATUS

approved

editing

#10 by Joerg Arndt at Wed Sep 05 11:13:44 EDT 2018

STATUS

reviewed

approved

#9 by Peter Luschny at Wed Sep 05 11:09:46 EDT 2018

STATUS

proposed

reviewed

#8 by Peter Luschny at Wed Sep 05 11:09:34 EDT 2018

STATUS

editing

proposed

#7 by Peter Luschny at Wed Sep 05 11:09:19 EDT 2018

MAPLE

A318874 := n -> nops(select(d -> (2*numtheory:-phi(d)) > d, divisors(n))):

seq(A318874(n), n=1..99); # Peter Luschny, Sep 05 2018

STATUS

proposed

editing

#6 by Antti Karttunen at Wed Sep 05 10:14:42 EDT 2018

STATUS

editing

proposed

#5 by Antti Karttunen at Wed Sep 05 10:12:25 EDT 2018

LINKS

Antti Karttunen, <a href="/A318874/b318874.txt">Table of n, a(n) for n = 1..65537</a>