OFFSET
1,1
COMMENTS
The generalization of this sequence is possible with the primes of the form (b^n +-k)*b^n +-1.
The corresponding n are in A200816.
For n = 166, a(10) has 100 digits; for n = 327, a(11) has 197 digits; for n = 460, a(12) has 277 digits; for n = 1108, a(13) has 668 digits; for n = 4740, a(14) has 2854 digits; for n = 20760, a(15) has 12499 digits; for n = 21143, a(16) has 12730 digits.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..14
Henri Lifchitz, De nouvelles formes de nombres premiers.
EXAMPLE
193 is in the sequence because (2^4 - 4)*2^4 + 1 = 193 is prime.
MATHEMATICA
a={}; Do[p=(2^n - n)*2^n + 1; If[PrimeQ[p], AppendTo[a, p]], {n, 5000}]; Print[a]
Select[Table[(2^n - n) 2^n + 1, {n, 0, 200}], PrimeQ] (* Vincenzo Librandi, Mar 15 2013 *)
PROG
(Magma) [a: n in [0..200] | IsPrime(a) where a is (2^n-n)*2^n+1]; // Vincenzo Librandi, Mar 15 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Lagneau, Nov 23 2011
EXTENSIONS
Added the term 2 from Vincenzo Librandi, Mar 15 2013
STATUS
approved