The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A153208 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A153208

Primes of the form 2*p-1 where p is prime and p-1 is not squarefree.
(history; published version)

#16 by Harvey P. Dale at Sun Aug 11 10:58:13 EDT 2024

STATUS

editing

approved

#15 by Harvey P. Dale at Sun Aug 11 10:58:09 EDT 2024

MATHEMATICA

Select[2#-1&/@Select[Prime[Range[1000]], !SquareFreeQ[#-1]&], PrimeQ] (* Harvey P. Dale, Aug 11 2024 *)

STATUS

approved

editing

#14 by OEIS Server at Wed Nov 22 22:21:42 EST 2023

LINKS

Robert Israel, <a href="/A153208/b153208_1.txt">Table of n, a(n) for n = 1..10000</a>

#13 by N. J. A. Sloane at Wed Nov 22 22:21:42 EST 2023

STATUS

proposed

approved

Discussion

Wed Nov 22

22:21

OEIS Server: Installed first b-file as b153208.txt.

#12 by Robert Israel at Wed Nov 22 21:37:23 EST 2023

STATUS

editing

proposed

#11 by Robert Israel at Wed Nov 22 21:37:09 EST 2023

LINKS

Robert Israel, <a href="/A153208/b153208_1.txt">Table of n, a(n) for n = 1..10000</a>

MAPLE

R:= NULL; count:= 0: p:= 3:

while count < 100 do

p:= nextprime(p);

if isprime(2*p-1) and not numtheory:-issqrfree(p-1) then

R:= R, 2*p-1; count:= count+1;

fi

od:

R; # Robert Israel, Nov 22 2023

STATUS

approved

editing

#10 by Charles R Greathouse IV at Thu Sep 08 08:45:39 EDT 2022

PROG

(MAGMAMagma) [ q: p in PrimesUpTo(2900) | not IsSquarefree(p-1) and IsPrime(q) where q is 2*p-1 ];

Discussion

Thu Sep 08

08:45

OEIS Server: https://oeis.org/edit/global/2944

#9 by Jon E. Schoenfield at Wed Dec 23 22:12:40 EST 2015

STATUS

editing

approved

#8 by Jon E. Schoenfield at Wed Dec 23 22:12:38 EST 2015

CROSSREFS

Cf. A013929 (not squarefree nonsquarefree numbers), A005383 (numbers n such that both n and (n+1)/2 are primes), A153207, A153209, A153210.

STATUS

approved

editing

#7 by Joerg Arndt at Fri Jul 05 04:59:47 EDT 2013

STATUS

proposed

approved