A236070 Primes p such that f(f(p)) is prime where f(x) = x^8 + 1.

7, 59, 163, 929, 977, 1373, 1549, 1619, 1913, 2113, 2593, 4397, 5417, 5651, 6397, 6659, 6833, 7351, 7793, 7883, 8641, 9719, 10091, 10477, 10949, 11243, 12239, 13441, 13457, 13691, 14753, 15349, 15467, 15971, 17747, 19051

Offset

1,1

Links

Table of n, a(n) for n=1..36.

Formula

a(n) = (A235983(n)-1)^(1/8).

Example

1619 is prime and (1619^8+1)^8+1 is also prime.

Mathematica

Select[Prime[Range[2500]], PrimeQ[(#^8+1)^8+1]&] (* Harvey P. Dale, Dec 17 2022 *)

Prog

(Python)
import sympy
from sympy import isprime
{print(p) for p in range(10**5) if isprime(p) and isprime((p**8+1)**8+1)}
(PARI) isok(p) = isprime(p) && (q = p^8+1) && isprime(q^8+1); \\ Michel Marcus, Jan 19 2014

Crossrefs

Cf. A235983.

Sequence in context: A140371 A181424 A142511 * A059705 A359691 A218201

Adjacent sequences: A236067 A236068 A236069 * A236071 A236072 A236073

Keyword

nonn

Author

Michel Marcus and Derek Orr, Jan 19 2014

Status

approved