A228225 Numbers n such that (17^n + 3^n)/20 is prime.

37, 641, 2521, 7993, 41213

Offset

1,1

Comments

All terms are primes.

a(6) > 10^5.

Links

Table of n, a(n) for n=1..5.

Mathematica

k=17; Do[ p=Prime[n]; f=(3^p+k^p)/(k+3); If[ PrimeQ[f], Print[p]], {n, 1, 9592} ]

Prog

(PARI) is(n)=ispseudoprime((17^n+3^n)/20) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A128073, A224507, A128075, A227046.

Sequence in context: A105464 A140764 A348301 * A156923 A338003 A104180

Adjacent sequences: A228222 A228223 A228224 * A228226 A228227 A228228

Keyword

hard,more,nonn

Author

Robert Price, Aug 16 2013

Status

approved