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
KEYWORD
nonn
AUTHOR
James R. Buddenhagen, Oct 24 2015
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