The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A125272 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A125272

Primes p such that 3p - 2 and 3p + 2 are also primes.
(history; published version)

#17 by Charles R Greathouse IV at Thu Sep 08 08:45:28 EDT 2022

PROG

(MAGMAMagma) [p: p in PrimesUpTo(70000)| IsPrime(3*p-2)and IsPrime(3*p+2)] // Vincenzo Librandi, Jan 29 2011

Discussion

Thu Sep 08

08:45

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

#16 by Harvey P. Dale at Sat May 29 13:31:22 EDT 2021

STATUS

editing

approved

#15 by Harvey P. Dale at Sat May 29 13:31:18 EDT 2021

MATHEMATICA

Select[Prime[Range[600]], AllTrue[3#+{2, -2}, PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, May 29 2021 *)

STATUS

approved

editing

#14 by Joerg Arndt at Mon Jan 22 02:26:14 EST 2018

STATUS

reviewed

approved

#13 by Michel Marcus at Mon Jan 22 02:09:32 EST 2018

STATUS

proposed

reviewed

#12 by Jon E. Schoenfield at Sun Jan 21 15:42:02 EST 2018

STATUS

editing

proposed

#11 by Jon E. Schoenfield at Sun Jan 21 15:41:59 EST 2018

NAME

Primes p such that 3p -/ 2 and 3p + 2 are also primes.

FORMULA

a(n) = A125215(n)/3.

PROG

(MAGMA) [p: p in PrimesUpTo(70000)| IsPrime(3*p-2)and IsPrime(3*p+2)] [From // _Vincenzo Librandi, _, Jan 29 2011]

STATUS

approved

editing

#10 by Charles R Greathouse IV at Tue Jul 02 09:53:00 EDT 2013

STATUS

editing

approved

#9 by Charles R Greathouse IV at Tue Jul 02 09:52:59 EDT 2013

KEYWORD

nonn,changed,easy

#8 by Charles R Greathouse IV at Tue Jul 02 09:52:51 EDT 2013

LINKS

Charles R Greathouse IV, <a href="/A125272/b125272.txt">Table of n, a(n) for n = 1..10000</a>

MATHEMATICA

lst={}; Do[p=Prime[n]; If[PrimeQ[3*p-2]&&PrimeQ[3*p+2], AppendTo[lst, p]], {n, 7!}]; lst [From _(* _Vladimir Joseph Stephan Orlovsky_, Jan 18 2009] *)

PROG

(PARI) is(n)=isprime(3*n-2)&&isprime(3*n+2)&&isprime(n) \\ Charles R Greathouse IV, Jul 02 2013

STATUS

approved

editing