The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A005122

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A005122

Numbers k such that 8k - 1 is prime.
(history; published version)

#38 by Joerg Arndt at Mon Feb 05 00:54:38 EST 2024

STATUS

editing

approved

#37 by Joerg Arndt at Mon Feb 05 00:54:15 EST 2024

MATHEMATICA

a={}; Do[x=8*n-1; If[PrimeQ[x], AppendTo[a, n]], {n, 10^2}]; a (* Vladimir Joseph Stephan Orlovsky, Apr 29 2008 *)

PROG

(PARI) lista(nn) = my(p, s, x, z); forprime(p = 3, nn, s = []; for(x = 0, p-1, if(x^4%p == 2%p, s = concat(s, [x]))); z = matsize(s)[2]; if(z == 2, print1((p+1)/8, ", "))) \\ Altug Alkan, Dec 10 2015

#36 by Jon E. Schoenfield at Sun Feb 04 16:28:23 EST 2024

NAME

Numbers n k such that 8n 8k - 1 is prime.

#35 by Paolo P. Lava at Sun Feb 04 13:55:26 EST 2024

COMMENTS

Solutions of the equation (8*n-1)'=1, where n' is the arithmetic derivative of n. - Paolo P. Lava, Jan 03 2013

STATUS

approved

editing

#34 by Charles R Greathouse IV at Thu Sep 08 08:44:33 EDT 2022

PROG

(MAGMAMagma) [n: n in [1..200] | IsPrime(8*n-1)]; // Vincenzo Librandi, Dec 10 2015

Discussion

Thu Sep 08

08:44

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

#33 by Peter Luschny at Sat Dec 12 08:02:39 EST 2015

STATUS

reviewed

approved

#32 by Joerg Arndt at Sat Dec 12 02:07:06 EST 2015

STATUS

proposed

reviewed

#31 by Wesley Ivan Hurt at Fri Dec 11 20:20:37 EST 2015

STATUS

editing

proposed

Discussion

Sat Dec 12

02:07

Joerg Arndt: Yes, local() is essentially obsolete.

#30 by Wesley Ivan Hurt at Fri Dec 11 20:20:11 EST 2015

MAPLE

A005122:=n->`if`(isprime(8*n-1), n, NULL): seq(A005122(n), n=1..300); # Wesley Ivan Hurt, Dec 11 2015

MATHEMATICA

Select[Range[160], PrimeQ[8#-1]&] (* Harvey P. Dale, Nov 25 2011 *)

STATUS

proposed

editing

#29 by Altug Alkan at Thu Dec 10 16:45:55 EST 2015

STATUS

editing

proposed