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A323033 Numbers k such that 381*2^k+1 is prime. 1
3, 15, 17, 20, 21, 41, 44, 51, 113, 140, 179, 219, 249, 323, 461, 521, 671, 680, 692, 695, 716, 809, 825, 887, 897, 1055, 1439, 1641, 2873, 4103, 4593, 6912, 9551, 13472, 21131, 23403, 101225, 104471, 135993, 163931, 169824, 182969, 224085, 273672, 287543 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Jeppe Stig Nielsen, Table of n, a(n) for n = 1..57 (terms n = 1..55 from Robert Price)

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for 300 < k < 600

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Eric Weisstein's World of Mathematics, Proth Prime

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

MAPLE

select(k->isprime(381*2^k+1), [$1..1000]); # Muniru A Asiru, Jan 02 2019

MATHEMATICA

Select[Range[1000], PrimeQ[381*2^# + 1] &] (* Robert Price, Jan 02 2019 *)

CROSSREFS

Sequence in context: A029476 A154317 A291122 * A080705 A032921 A163785

Adjacent sequences:  A323030 A323031 A323032 * A323034 A323035 A323036

KEYWORD

nonn,hard

AUTHOR

Robert Price, Jan 02 2019

STATUS

approved

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Last modified October 24 20:35 EDT 2021. Contains 348233 sequences. (Running on oeis4.)