login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A032411 Numbers k such that 123*2^k+1 is prime. 0
6, 8, 17, 21, 29, 32, 46, 57, 69, 128, 141, 268, 333, 476, 742, 832, 1173, 1677, 5068, 9568, 15453, 34761, 39992, 41213, 41852, 93982, 100748, 102929, 164069, 286268, 561012, 582672, 875878, 1107008, 3049038 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..35.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

MATHEMATICA

Select[Range[1000], PrimeQ[123*2^# + 1] & ] (* Robert Price, Dec 17 2018 *)

PROG

(PARI) is(n)=ispseudoprime(123*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A315941 A025081 A162951 * A345034 A058098 A112158

Adjacent sequences:  A032408 A032409 A032410 * A032412 A032413 A032414

KEYWORD

nonn,hard,more

AUTHOR

James R. Buddenhagen

EXTENSIONS

Extended by Hugo Pfoertner, Jul 02 2003

a(30)-a(34) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 17 2018

a(35) from Jeppe Stig Nielsen, Jan 19 2020

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)