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A032477
Numbers k such that 201*2^k+1 is prime.
0
3, 4, 9, 60, 72, 75, 84, 348, 592, 1348, 1380, 1632, 1855, 2335, 4528, 9813, 17103, 28935, 34023, 100459, 243544, 281865, 371844, 648792, 812035, 886480, 2080464
OFFSET
1,1
MATHEMATICA
Select[Range[1000], PrimeQ[201*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)
PROG
(PARI) is(n)=ispseudoprime(201*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A225467 A225473 A015240 * A073015 A364376 A240546
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
a(20)-a(26) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018
a(27) from Jeppe Stig Nielsen, May 30 2020
STATUS
approved