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A032490 Numbers k such that 227*2^k+1 is prime. 0
11, 15, 35, 51, 83, 87, 99, 183, 4619, 4659, 6939, 7503, 10647, 13007, 18459, 19599, 26363, 43719, 53171, 140679, 249599, 308139, 797603, 1542323, 1786779 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..25.

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

Ray Ballinger, Proth Search Page

MATHEMATICA

Select[Range[1000], PrimeQ[227*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

PROG

(PARI) is(n)=ispseudoprime(227*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A085597 A316643 A097512 * A068483 A241679 A219389

Adjacent sequences:  A032487 A032488 A032489 * A032491 A032492 A032493

KEYWORD

nonn,hard,more

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(20)-a(25) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

STATUS

approved

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Last modified July 5 04:30 EDT 2020. Contains 335459 sequences. (Running on oeis4.)