The On-Line Encyclopedia of Integer Sequences (OEIS)

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Revision History for A058524

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Each c(i) is "multiply" (*) or "divide" (/). a(n) is number of choices for c(1), ..., c(n-1) so that 1 c(1) 2 c(2) 3,.., c(n-1) n is an integer.
(history; published version)

#8 by Michael De Vlieger at Sun Aug 07 22:10:29 EDT 2022

STATUS

proposed

approved

#7 by Sean A. Irvine at Sun Aug 07 21:31:47 EDT 2022

STATUS

editing

proposed

#6 by Sean A. Irvine at Sun Aug 07 21:31:01 EDT 2022

DATA

1, 1, 1, 2, 2, 8, 8, 13, 21, 77, 77, 128, 128, 354, 641, 1232, 1232, 2677, 2677, 7220, 8951, 25378, 25378, 63680, 113335, 323151, 532358, 1442702, 1442702, 2963955, 2963955, 5307221, 6739508, 21786788, 41416560, 83691901, 83691901, 242224403, 373640477, 669300795, 669300795

LINKS

Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a058/A058524.java">Java program</a> (github)

FORMULA

a(p) = a(p-1). - Sean A. Irvine, Aug 07 2022

KEYWORD

nonn,easy,nice

EXTENSIONS

a(31)-a(41) from Sean A. Irvine, Aug 07 2022

STATUS

approved

editing

#5 by Russ Cox at Sat Mar 31 13:50:36 EDT 2012

AUTHOR

_Naohiro Nomoto (6284968128(AT)geocities.co.jp), _, Dec 22 2000

Discussion

Sat Mar 31

13:50

OEIS Server: https://oeis.org/edit/global/906

#4 by Russ Cox at Sat Mar 31 10:22:53 EDT 2012

EXTENSIONS

More terms from _Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), _, Oct 14 2001

Discussion

Sat Mar 31

10:22

OEIS Server: https://oeis.org/edit/global/354

#3 by N. J. A. Sloane at Wed Sep 22 03:00:00 EDT 2004

KEYWORD

nonn,easy,nice,new

EXTENSIONS

More terms from Sascha Kurz (sascha.kurz(AT)stud.uni-bayreuth.de), Oct 14 2001

#2 by N. J. A. Sloane at Sat Sep 13 03:00:00 EDT 2003

KEYWORD

nonn,easy,nice,new

EXTENSIONS

More terms from Sascha Kurz (ssascha.kurz(AT)tustud.uni-bsbayreuth.de), Oct 14 2001

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

Each c(i) is "multiply" (*) or "divide" (/). a(n) is number of choices for c(1), ..., c(n-1) so that 1 c(1) 2 c(2) 3,.., c(n-1) n is an integer.

DATA

1, 1, 1, 2, 2, 8, 8, 13, 21, 77, 77, 128, 128, 354, 641, 1232, 1232, 2677, 2677, 7220, 8951, 25378, 25378, 63680, 113335, 323151, 532358, 1442702, 1442702, 2963955

OFFSET

1,4

EXAMPLE

For n = 4 there are 2 possibilities: 1*2*3*4=24 and 1/2*3*4=6. For n = 9 there are 13 possibilities: 1*2*3*4*5*6*7*8 1/2*3*4*5*6*7*8 1/2/3*4*5*6*7*8 1*2/3*4*5*6*7*8 1*2*3*4*5/6*7*8 1*2*3/4*5*6*7*8 1*2/3/4*5*6*7*8 1/2*3*4*5/6*7*8 1/2*3/4*5*6*7*8 1/2/3/4*5*6*7*8 1*2*3*4*5*6*7/8 1*2/3*4*5*6*7/8 1*2*3/4*5/6*7*8.

KEYWORD

nonn,easy,nice

AUTHOR

Naohiro Nomoto (6284968128(AT)geocities.co.jp), Dec 22 2000

EXTENSIONS

More terms from Sascha Kurz (s.kurz(AT)tu-bs.de), Oct 14 2001

STATUS

approved