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A032456 Numbers k such that 159*2^k + 1 is prime. 0
6, 7, 9, 18, 19, 22, 30, 34, 42, 106, 190, 262, 339, 354, 379, 478, 523, 690, 718, 855, 963, 1087, 2478, 3309, 3862, 4155, 5098, 6678, 12898, 14226, 14274, 18738, 20065, 24390, 44079, 103417, 108850, 112374, 142462, 280438, 514927, 650934, 689437, 1579426 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The subsequence of prime values starts 7, 19, 379, 523, 1087, ... - Muniru A Asiru, Apr 28 2019

LINKS

Table of n, a(n) for n=1..44.

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

MAPLE

select(k->isprime(159*2^k+1), [$0..1000]); # Muniru A Asiru, Dec 21 2018

MATHEMATICA

Select[Range[1000], PrimeQ[159*2^# + 1] & ] (* Robert Price, Dec 18 2018 *)

PROG

(PARI) is(n)=ispseudoprime(159*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

(MAGMA) [n: n in [1..1000] | IsPrime(159*2^n+1)]; // G. C. Greubel, Apr 28 2019

(Sage) [n for n in (1..1000) if is_prime(159*2^n+1)] # G. C. Greubel, Apr 28 2019

(GAP) Filtered([1..1000], k-> IsPrime(159*2^k+1)); # G. C. Greubel, Apr 28 2019

CROSSREFS

Sequence in context: A289547 A329912 A187922 * A228442 A328644 A164989

Adjacent sequences:  A032453 A032454 A032455 * A032457 A032458 A032459

KEYWORD

nonn,hard

AUTHOR

N. J. A. Sloane

EXTENSIONS

a(36)-a(44) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 18 2018

STATUS

approved

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Last modified February 27 15:59 EST 2020. Contains 332307 sequences. (Running on oeis4.)