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A032496 Numbers k such that 239*2^k+1 is prime. 0
1, 3, 5, 7, 17, 29, 31, 89, 135, 229, 257, 305, 493, 781, 811, 1177, 1315, 1709, 2267, 5283, 6109, 7763, 7923, 16481, 18457, 29187, 39487, 53393, 59905, 59905, 76267, 109325, 278595, 307745, 547433, 651413, 1072433, 1936025 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..38.

Ray Ballinger, Proth Search Page

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

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

MATHEMATICA

Select[Range[1000], PrimeQ[239*2^# + 1] & ] (* Robert Price, Dec 20 2018 *)

PROG

(PARI) is(n)=ispseudoprime(239*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A141772 A220454 A257592 * A002092 A274906 A296422

Adjacent sequences:  A032493 A032494 A032495 * A032497 A032498 A032499

KEYWORD

nonn,hard,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(30)-a(38) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 20 2018

STATUS

approved

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Last modified August 24 16:39 EDT 2019. Contains 326295 sequences. (Running on oeis4.)