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A281483 Numbers k such that 32771*2^k + 1 is prime. 0
1, 13, 19, 29, 37, 45, 51, 61, 63, 65, 69, 117, 171, 181, 199, 201, 217, 221, 265, 337, 627, 631, 881, 1035, 1507, 1525, 1627, 1641, 2037, 3175, 4639, 6445, 21537, 29801, 30521, 30917, 37877, 49725, 50877, 57537, 61337, 118141, 125169, 200961, 204117, 283445, 395125, 829489 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(48) = 829489, 1438879 is such that 32771*2^1438879 + 1 is prime with 433151 digits, 829489 < a(49) <= 1438879.

LINKS

Table of n, a(n) for n=1..48.

MATHEMATICA

Select[Range@ 3000, PrimeQ[32771*2^# + 1] &] (* Michael De Vlieger, Jan 23 2017 *)

PROG

(PFGW) 32771*2^$a+1

$a: from 1 to 1000001 step 2

(PARI) list(limit)=my(i=1); while(i<limit, if(isprime(32771*2^i+1), print1(i, ", ")); i++) \\ Anders Hellström, Feb 04 2017

CROSSREFS

Cf. A002253.

Sequence in context: A103804 A063640 A092104 * A094105 A073620 A089391

Adjacent sequences:  A281480 A281481 A281482 * A281484 A281485 A281486

KEYWORD

nonn

AUTHOR

Pierre CAMI, Jan 22 2017

STATUS

approved

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Last modified May 18 05:01 EDT 2021. Contains 343994 sequences. (Running on oeis4.)