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A032492 Numbers k such that 231*2^k+1 is prime. 1
1, 4, 5, 7, 9, 11, 12, 13, 15, 27, 33, 65, 85, 89, 105, 120, 149, 161, 175, 229, 279, 295, 307, 355, 453, 528, 625, 697, 807, 831, 879, 901, 935, 988, 1265, 1432, 1645, 1761, 1899, 1939, 2497, 3101, 5176, 5181, 9809, 14025, 21765, 27333, 35271, 36717, 40935 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..76 (terms n = 1..72 from Robert Price)

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[231*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)

PROG

(PARI) is(n)=ispseudoprime(231*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A191771 A267027 A267865 * A223134 A267087 A050560

Adjacent sequences:  A032489 A032490 A032491 * A032493 A032494 A032495

KEYWORD

nonn,hard

AUTHOR

N. J. A. Sloane.

EXTENSIONS

a(51)-a(72) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018

STATUS

approved

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Last modified July 6 23:56 EDT 2020. Contains 335484 sequences. (Running on oeis4.)