The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A111928

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A111928

Numerator of f(n) := Product_{i=1..n} sigma(i)/i.
(history; published version)

#14 by Harvey P. Dale at Sun Jan 17 12:47:42 EST 2016

STATUS

editing

approved

#13 by Harvey P. Dale at Sun Jan 17 12:47:37 EST 2016

LINKS

Harvey P. Dale, <a href="/A111928/b111928.txt">Table of n, a(n) for n = 1..808</a>

STATUS

approved

editing

#12 by Harvey P. Dale at Sun Jan 17 12:45:43 EST 2016

STATUS

editing

approved

#11 by Harvey P. Dale at Sun Jan 17 12:45:36 EST 2016

MATHEMATICA

Numerator[FoldList[Times, Table[DivisorSigma[1, n]/n, {n, 30}]]] (* Harvey P. Dale, Jan 17 2016 *)

STATUS

approved

editing

#10 by Bruno Berselli at Mon Feb 16 10:23:53 EST 2015

STATUS

proposed

approved

#9 by Jon E. Schoenfield at Mon Feb 16 09:10:28 EST 2015

STATUS

editing

proposed

#8 by Jon E. Schoenfield at Mon Feb 16 09:10:25 EST 2015

COMMENTS

_R. K. Guy _ observes (Nov 23, 2005) that it appears that f(n) is an integer iff n = 1, 3, 8, 9, when f(n) = 1, 2, 18, 26 respectively.

MATHEMATICA

f[n_] := Numerator@ Product[ DivisorSigma[1, i]/i, {i, n}]; Array[f, 30] (from _* _Robert G. Wilson v_, May 01 2006 *)

STATUS

approved

editing

#7 by Charles R Greathouse IV at Sat Jul 14 11:40:56 EDT 2012

MATHEMATICA

f[n_] := Numerator@ Product[ DivisorSigma[1, i]/i, {i, n}]; Array[f, 30] (from _Robert G. Wilson v (rgwv(at)rgwv.com), _, May 01 2006)

Discussion

Sat Jul 14

11:40

OEIS Server: https://oeis.org/edit/global/1816

#6 by Russ Cox at Fri Mar 30 16:50:20 EDT 2012

AUTHOR

_N. J. A. Sloane (njas(AT)research.att.com), _, Nov 27 2005

Discussion

Fri Mar 30

16:50

OEIS Server: https://oeis.org/edit/global/110

#5 by N. J. A. Sloane at Fri Feb 27 03:00:00 EST 2009

KEYWORD

nonn,frac,new

AUTHOR

N. J. A. Sloane (njas, (AT)research.att.com), Nov 27 2005