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A032410
Numbers k such that 121*2^k+1 is prime.
1
8, 12, 44, 84, 96, 228, 264, 320, 732, 788, 1808, 7928, 12264, 37784, 59196, 91112, 112208, 168716, 251184, 264632, 272052, 513020, 636564, 674360
OFFSET
1,1
COMMENTS
9584444 is also a term (cf. PrimeGrid, 2020). - Felix Fröhlich, Dec 10 2020
MATHEMATICA
Select[Range[1000], PrimeQ[121*2^# + 1] & ] (* Robert Price, Dec 17 2018 *)
PROG
(PARI) is(n)=ispseudoprime(121*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Cf. A050586.
Sequence in context: A281663 A092179 A269726 * A077101 A229497 A009926
KEYWORD
nonn,hard,more
EXTENSIONS
Extended by Hugo Pfoertner, Jul 02 2003
a(20)-a(24) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 17 2018
STATUS
approved