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A050595 Numbers k such that 139*2^k-1 is prime. 0
1, 5, 7, 9, 15, 19, 21, 35, 37, 39, 41, 49, 69, 111, 115, 141, 159, 181, 201, 217, 487, 567, 677, 765, 811, 841, 917, 1279, 1407, 1505, 1521, 1587, 2047, 2469, 2649, 3019, 7427, 10257, 33685, 34479, 35177, 43641, 49211, 65031, 84907, 90231, 95021, 124375, 176425, 224947, 382441, 451367 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..52.

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

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

Kosmaj, Riesel list 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[139*2^# - 1] & ] (* Robert Price, Dec 23 2018 *)

PROG

(PARI) is(n)=ispseudoprime(139*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A327307 A029606 A247283 * A182029 A177941 A029667

Adjacent sequences:  A050592 A050593 A050594 * A050596 A050597 A050598

KEYWORD

hard,nonn

AUTHOR

N. J. A. Sloane, Dec 29 1999

EXTENSIONS

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

a(49)-a(52) from the Wilfrid Keller link by Robert Price, Dec 23 2018

STATUS

approved

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Last modified September 30 18:12 EDT 2020. Contains 337440 sequences. (Running on oeis4.)