A128075 - OEIS

A128075

Numbers k such that (3^k + 19^k)/22 is prime.

3, 61, 71, 109, 9497, 36007, 50461, 66919

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OFFSET

1,1

COMMENTS

All terms are primes.

a(9) > 10^5. - Robert Price, Jul 21 2013

LINKS

MATHEMATICA

k=19; Do[ p=Prime[n]; f=(3^p+k^p)/(k+3); If[ PrimeQ[f], Print[p]], {n, 1, 9592} ]

PROG

(PARI) is(n)=isprime((3^n+19^n)/22) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A007658 (numbers k such that (3^k + 1)/4 is prime).

Cf. A057469 (numbers k such that (3^k + 2^k)/5 is prime).

Cf. A122853 (numbers k such that (3^k + 5^k)/8 is prime).

Cf. A059801 (numbers k such that 4^k - 3^k is prime).

Cf. A121877 (numbers k such that (5^k - 3^k)/2 is prime).

KEYWORD

hard,more,nonn

AUTHOR

EXTENSIONS

a(5)-a(8) from Robert Price, Jul 21 2013

STATUS

approved