A165991 Numbers n such that 3 + 2^n is not prime.
0, 5, 8, 9, 10, 11, 13, 14, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 29, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87
Offset: 1
Examples
For n=0, 3+2^0=4 is not prime. n=5, 3+2^5=35=5*7, not prime. n=8, 3+2^8=259=7*37 not prime.
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Programs
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Magma
[n: n in [0..100] |not IsPrime(3 + 2^n )]; // Vincenzo Librandi, Oct 15 2012
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Mathematica
Select[Range[0, 100], !PrimeQ[3 + 2^#] &] (* Vincenzo Librandi, Oct 15 2012 *)
Extensions
Entries checked - R. J. Mathar, Oct 05 2009
Comments