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A032480
Numbers k such that 207*2^k + 1 is prime.
1
2, 3, 4, 6, 7, 10, 14, 15, 16, 34, 42, 44, 46, 62, 66, 106, 127, 130, 171, 202, 231, 232, 238, 248, 256, 296, 314, 412, 604, 956, 1023, 1287, 1454, 1564, 1766, 2036, 5215, 5911, 6092, 9190, 9916, 10410, 13456, 14336, 14444, 15490, 30835, 32558, 34770, 41218
OFFSET
1,1
LINKS
MATHEMATICA
f[n_]:=PrimeQ[207*2^n+1]; lst={}; Do[If[f[n], AppendTo[lst, n]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Mar 03 2010 *)
Select[Range[1000], PrimeQ[207*2^# + 1] & ] (* Robert Price, Dec 19 2018 *)
PROG
(PARI) is(n)=ispseudoprime(207*2^n+1) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
Sequence in context: A035941 A039854 A237752 * A226137 A355393 A163771
KEYWORD
nonn,hard
EXTENSIONS
a(50)-a(66) from the Ray Ballinger and Wilfrid Keller link by Robert Price, Dec 19 2018
STATUS
approved