A128030 Numbers k such that (16^k - 3^k)/13 is prime.

2, 3, 31, 467, 1747, 29683

Offset

1,1

Comments

All terms are primes.

No other terms < 100000.

Links

Table of n, a(n) for n=1..6.

Mathematica

k=13; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]

Prog

(PARI) is(n)=isprime((16^n-3^n)/13) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Cf. A028491 = numbers n such that (3^n - 1)/2 is prime. Cf. A057468 = numbers n such that 3^n - 2^n is prime. Cf. A059801 = numbers n such that 4^n - 3^n is prime. Cf. A121877 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128024, A128025, A128026, A128027, A128028, A128029, A128031, A128032.

Sequence in context: A049065 A274609 A372142 * A239593 A214658 A334489

Adjacent sequences: A128027 A128028 A128029 * A128031 A128032 A128033

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 11 2007

Extensions

1747 from Farideh Firoozbakht, Apr 08 2007

a(6)=29683 from Robert Price, Sep 13 2011

Status

approved