OFFSET
1,1
COMMENTS
Subsequence of A000051.
Prime terms are in A268210: 2, 3, 5, 17, 65537, ...
Corresponding values of numbers k are in A100361 (numbers n such that 2^n-n+1 is prime).
Corresponding values of primes q are in A100362 (primes of the form 2^n-n+1).
4 out of 5 known Fermat primes (3, 5, 17, 65537) are terms; corresponding values of primes q: 2, 3, 13, 65521.
LINKS
Jaroslav Krizek, Table of n, a(n) for n = 1..12
EXAMPLE
17 = 2^4 + 1 is a term because 17 - 4 = 13 (prime).
257 = 2^8 + 1 is not a term because 257 - 8 = 249 (composite number).
MATHEMATICA
2^# + 1 &@ Select[Range[0, 600], PrimeQ[2^# - # + 1] &] (* Michael De Vlieger, Jan 29 2016 *)
PROG
(Magma) [2^k + 1: k in [0..60] | IsPrime(2^k - k + 1)]
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jan 28 2016
STATUS
approved