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Revision History for A066523

(Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A066523 Crowded numbers: for any k in the sequence, d(k)/k is larger than d(m)/m for all m > k.
(history; published version)
#22 by N. J. A. Sloane at Fri Jul 19 19:03:57 EDT 2024
STATUS

proposed

approved

#21 by Jon E. Schoenfield at Fri Jul 19 18:45:06 EDT 2024
STATUS

editing

proposed

#20 by Jon E. Schoenfield at Fri Jul 19 18:44:59 EDT 2024
CROSSREFS

Cf. A002182, A000005, A004394, A354768.

STATUS

proposed

editing

#19 by Jon E. Schoenfield at Fri Jul 19 18:42:42 EDT 2024
STATUS

editing

proposed

#18 by Jon E. Schoenfield at Fri Jul 19 18:42:38 EDT 2024
NAME

Crowded numbers: for any nk in the sequence, d(nk)/nk is larger than d(m)/m for all m > nk.

COMMENTS

Since d(m) < 2*sqrt(m), we need only test values of m < (2n2k/d(nk))^2.

Additional comments from Roy Maulbogat, Jan 22 2008: (Start)

Additional comments from Roy Maulbogat, Jan 22 2008: (Start) It can easily be shown that all crowded numbers are even and that there is always a crowded number between N and 2N. This allows us to improve the algorithm as followfollows:

crowded[nk_] := Module[{},

* If[OddQ[nk], Return [False]];*

div = DivisorSigma[0,nk]/nk;

For [ *m=nk+2, m<=2n2k, m+=2*, If[

On second thought, it might be wise to use Min[2n2k, stop] as the stopping condition of the loop ("stop" being the variable defined in the original algorithm). (End)

LINKS

Roy Maulbogat and Donovan Johnson, <a href="/A066523/b066523.txt">Table of n, a(n) for n = 1..300</a> (first 129 terms from Roy Maulbogat)

EXTENSIONS

Edited by Dean Hickerson, Jan 07, 2002.

STATUS

approved

editing

#17 by Sean A. Irvine at Tue Oct 24 00:30:25 EDT 2023
STATUS

editing

approved

#16 by Sean A. Irvine at Tue Oct 24 00:30:19 EDT 2023
COMMENTS

On second thought, it might be wise to use Min[2n, stop] as the stoopingstopping condition of the loop ("stop" being the variable defined in the original algorithm). (End)

STATUS

approved

editing

#15 by N. J. A. Sloane at Tue Jun 24 01:08:18 EDT 2014
EXTENSIONS

Edited by _Dean Hickerson (dean.hickerson(AT)yahoo.com), _, Jan 07, 2002.

Discussion
Tue Jun 24 01:08
OEIS Server: https://oeis.org/edit/global/2238
#14 by OEIS Server at Mon Oct 08 19:11:02 EDT 2012
LINKS

Roy Maulbogat and Donovan Johnson, <a href="/A066523/b066523_1.txt">Table of n, a(n) for n = 1..300</a> (first 129 terms from Roy Maulbogat)

#13 by T. D. Noe at Mon Oct 08 19:11:02 EDT 2012
STATUS

editing

approved

Discussion
Mon Oct 08 19:11
OEIS Server: Installed new b-file as b066523.txt.  Old b-file is now b066523_1.txt.

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Last modified August 19 03:19 EDT 2024. Contains 375284 sequences. (Running on oeis4.)