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A322952 Numbers k such that 321*2^k+1 is prime. 0
1, 5, 32, 68, 109, 128, 133, 212, 241, 653, 776, 1339, 1787, 2659, 6388, 6547, 8365, 16699, 62861, 64795, 83227, 195376, 278875, 442480, 542876, 730321, 1168576, 1257859, 1629307 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..29.

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(n->isprime(321*2^n+1), [$1..1000]); # Muniru A Asiru, Dec 31 2018

MATHEMATICA

Select[Range[1000], PrimeQ[321*2^# + 1] &] (* Robert Price, Dec 31 2018 *)

CROSSREFS

Cf. A002255, A050527.

Sequence in context: A247549 A140154 A073694 * A101966 A341423 A184536

Adjacent sequences:  A322949 A322950 A322951 * A322953 A322954 A322955

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Dec 31 2018

STATUS

approved

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Last modified June 22 04:06 EDT 2021. Contains 345367 sequences. (Running on oeis4.)