OFFSET
0,1
LINKS
Robert Israel, Table of n, a(n) for n = 0..3310
FORMULA
a(n) << 37^n by Xylouris's improvement to Linnik's theorem. - Charles R Greathouse IV, Dec 10 2013
EXAMPLE
a(0)=2 because 2 = 3*2^0 - 1 is prime.
a(1)=3 because 3 = 2*2^1 - 1 is prime.
a(2)=3 because 3 = 1*2^2 - 1 is prime.
a(3)=7 because 7 = 1*2^3 - 1 is prime.
a(4)=31 because 31 = 2*2^4 - 1 is prime.
MAPLE
p:= 2: A[0]:= 2:
for n from 1 to 100 do
if p+1 mod 2^n = 0 then A[n]:= p
else
p:=p+2^(n-1);
while not isprime(p) do p:= p+2^n od:
A[n]:= p;
fi
od:
seq(A[i], i=0..100); # Robert Israel, Jan 13 2017
MATHEMATICA
a = {}; Do[k = 0; While[ !PrimeQ[k 2^n + 2^n - 1], k++ ]; AppendTo[a, k 2^n + 2^n - 1], {n, 0, 50}]; a (* Artur Jasinski, Jan 19 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Jan 19 2007
EXTENSIONS
Edited by Don Reble, Jun 11 2007
Further edited by N. J. A. Sloane, Jul 03 2008
STATUS
approved