login
A263718
n such that (1+2*7^n)/3 is prime.
0
1, 3, 4, 15, 24, 58, 168, 234, 324, 375, 3327, 5788, 8344, 15039, 59116, 62620
OFFSET
1,2
COMMENTS
The numbers corresponding to a(11)-a(16) are only (extra-strong BPSW) probable primes. - Charles R Greathouse IV, Nov 10 2015
MATHEMATICA
Select[Range@ 2000, PrimeQ[(1 + 2 7^#)/3] &] (* Michael De Vlieger, Nov 06 2015 *)
PROG
(PARI) is(n)=ispseudoprime((1+2*7^n)/3) \\ Charles R Greathouse IV, Nov 06 2015
CROSSREFS
Sequence in context: A065942 A369082 A036759 * A286675 A286025 A286645
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(11)-a(14) from Charles R Greathouse IV, Nov 06 2015
a(15)-a(16) from Charles R Greathouse IV, Nov 09 2015
STATUS
approved