OFFSET
1,1
COMMENTS
Corresponding values of k: 0, (2, 3), 4, 5, 8, 9, 16, 29, 213, 221, 233, ...; for the prime 5 there are two values: 2 and 3.
Fermat primes > 3 from A019434 are terms.
Prime terms from A269019.
a(16) > 2^16000 if it exists. - Robert Israel, Nov 11 2022
a(16) = 2^20757 - 3, a(17) = 2^30041 - 3. a(18) > 2^40000, if it exists. - Jon E. Schoenfield, Nov 11 2022
LINKS
Robert Israel, Table of n, a(n) for n = 1..15
MAPLE
Res:= 2, 5: count:= 2:
for n from 4 while count < 15 do
x:= 2^n + 2*(-1)^n - 1;
if isprime(x) then Res:= Res, x; count:= count+1 fi;
od:
Res; # Robert Israel, Nov 11 2022
PROG
(Magma) Set(Sort([2^n + 2*(-1)^n - 1: n in [0..300] | IsPrime(2^n + 2*(-1)^n - 1)]))
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Feb 17 2016
STATUS
approved