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A032505
Numbers n such that 257*2^n+1 is prime.
1
279, 415, 711, 115807, 241071
OFFSET
1,1
PROG
(PARI) is(n)=ispseudoprime(257*2^n+1) \\ Charles R Greathouse IV, Jun 07 2017
CROSSREFS
Sequence in context: A251624 A062384 A053345 * A252855 A331265 A038656
KEYWORD
nonn,hard
AUTHOR
EXTENSIONS
One more term (from the Ballinger-Keller web page) from M. F. Hasler, Apr 18 2007
STATUS
approved