

A032478


Numbers k such that 203*2^k + 1 is prime.


0



13, 25, 29, 33, 45, 57, 65, 153, 197, 245, 637, 1785, 1917, 2045, 4925, 5313, 7449, 8437, 23645, 28273, 34217, 40189, 135125, 141477, 169077, 215945, 234229, 265089, 482177, 556069, 1335989, 1357425, 1966689, 2526505
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OFFSET

1,1


LINKS

Table of n, a(n) for n=1..34.
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^n1 (or k*2^n+1) is prime


MATHEMATICA

Select[Range[0, 1000], PrimeQ[203*2^# + 1] &] (* Robert Price, Dec 09 2018 *)


PROG

(PARI) is(n)=ispseudoprime(203*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017


CROSSREFS

Sequence in context: A335374 A335466 A186403 * A280925 A161603 A075033
Adjacent sequences: A032475 A032476 A032477 * A032479 A032480 A032481


KEYWORD

nonn,hard


AUTHOR

N. J. A. Sloane


EXTENSIONS

a(25)a(32) from Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 09 2018
a(33) from updated Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 10 2018
a(34) from Jeppe Stig Nielsen, Apr 04 2020


STATUS

approved



