A032403 - OEIS

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A032403

Numbers k such that 107*2^k+1 is prime.

0

3, 7, 23, 27, 291, 303, 311, 479, 567, 3087, 18459, 33575, 43123, 58291, 155587, 173007, 414531, 1220391, 1337019, 2081775, 2401731

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..21.

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

PROG

(PARI) is(n)=ispseudoprime(107*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A355075 A173878 A225264 * A072584 A262250 A139513

Adjacent sequences: A032400 A032401 A032402 * A032404 A032405 A032406

KEYWORD

nonn,hard

AUTHOR

James R. Buddenhagen

EXTENSIONS

Extended by Hugo Pfoertner, Jul 02 2003

a(16)-a(20) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 14 2018

a(21) from Jeppe Stig Nielsen, Apr 04 2020

STATUS

approved