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A032365
Numbers k such that 31*2^k+1 is prime.
1
8, 60, 68, 140, 216, 416, 1808, 1944, 9096, 76596, 93168, 4673544, 5560820
OFFSET
1,1
PROG
(PARI) is(n)=ispseudoprime(31*2^n+1) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
Sequence in context: A186362 A285231 A264817 * A250315 A074423 A199906
KEYWORD
nonn,hard
EXTENSIONS
a(12) from Jeppe Stig Nielsen, Oct 14 2019
a(13) from Jeppe Stig Nielsen, Jan 29 2020
STATUS
approved