A263718 - OEIS

A263718

n such that (1+2*7^n)/3 is prime.

1, 3, 4, 15, 24, 58, 168, 234, 324, 375, 3327, 5788, 8344, 15039, 59116, 62620

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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

LINKS

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

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