The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A163489 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A163489

Indices n such that composite(n)/3 is prime.
(history; published version)

#12 by Harvey P. Dale at Sat Aug 06 17:24:33 EDT 2022

STATUS

editing

approved

#11 by Harvey P. Dale at Sat Aug 06 17:24:30 EDT 2022

MATHEMATICA

Position[Select[Range[1000], CompositeQ], _?(PrimeQ[#/3]&)]//Flatten (* Harvey P. Dale, Aug 06 2022 *)

STATUS

approved

editing

#10 by Bruno Berselli at Tue Apr 15 02:50:42 EDT 2014

STATUS

proposed

approved

#9 by Michel Marcus at Tue Apr 15 01:00:52 EDT 2014

STATUS

editing

proposed

#8 by Michel Marcus at Tue Apr 15 01:00:48 EDT 2014

EXAMPLE

a(1)=2 (2nd composite/3 = 6/3 = 2, which is prime); a(2)=4 (4th composite/3 = 9/3 = 3, which is prime).

a(2)=4 (4th composite/3 = 9/3 = 3, which is prime).

STATUS

proposed

editing

#7 by Jon E. Schoenfield at Mon Apr 14 22:41:28 EDT 2014

STATUS

editing

proposed

#6 by Jon E. Schoenfield at Mon Apr 14 22:41:25 EDT 2014

EXAMPLE

a(1)=2 (2th 2nd composite/3 = 6/3 = 2=, which is prime); a(2)=4 (4th composite/3 = 9/3 = 3=, which is prime).

EXTENSIONS

48 replaced by 49, 62 replaced by 63, 96 by 97 , etc. - R. J. Mathar, Oct 09 2009

STATUS

approved

editing

#5 by Russ Cox at Fri Mar 30 18:52:34 EDT 2012

AUTHOR

_Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), _, Jul 29 2009

Discussion

Fri Mar 30

18:52

OEIS Server: https://oeis.org/edit/global/257

#4 by Russ Cox at Fri Mar 30 17:40:05 EDT 2012

EXTENSIONS

48 replaced by 49, 62 replaced by 63, 96 by 97 etc. - _R. J. Mathar (mathar(AT)strw.leidenuniv.nl), _, Oct 09 2009

Discussion

Fri Mar 30

17:40

OEIS Server: https://oeis.org/edit/global/190

#3 by Charles R Greathouse IV at Fri May 27 01:05:31 EDT 2011

STATUS

proposed

approved