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A132829
Numbers k such that 3^k + 2 is not prime.
1
5, 6, 7, 9, 11, 12, 13, 16, 17, 18, 19, 20, 21, 22, 23, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83
OFFSET
1,1
MATHEMATICA
a = {}; c = 3^x + 2; Do[If[PrimeQ[c], 0, AppendTo[a, x]], {x, 0, 100}]; a
Select[Range[90], CompositeQ[3^#+2]&] (* Harvey P. Dale, Sep 25 2021 *)
PROG
(Magma) [n: n in [0..100]| not IsPrime(3^n+2)]; // Vincenzo Librandi, Jan 28 2011
CROSSREFS
Sequence in context: A089192 A279195 A232710 * A180061 A196029 A096820
KEYWORD
nonn
AUTHOR
Artur Jasinski, Sep 03 2007
STATUS
approved