A236069 Primes p such that f(f(p)) is prime where f(x) = x^4 + 1.

3, 79, 83, 107, 211, 401, 491, 881, 1013, 1061, 1367, 1637, 1669, 1811, 2029, 2309, 2399, 2459, 2671, 2713, 2963, 3109, 3203, 3407, 3593, 3709, 3733, 3929, 4219, 4457, 4513, 4639, 4703, 4729, 5417, 5641, 6047, 6113

Offset

1,1

Links

Table of n, a(n) for n=1..38.

Formula

a(n) = (A235982(n)-1)^(1/4).

Example

881 is prime and (881^4+1)^4+1 is also prime. So, 881 is a member of this sequence.

Prog

(Python)
import sympy
from sympy import isprime
{print(p) for p in range(10**4) if isprime(p) and isprime((p**4+1)**4+1)}
(PARI) isok(p) = isprime(p) && (q = p^4+1) && isprime(q^4+1); \\ Michel Marcus, Jan 19 2014

Crossrefs

Cf. A235982.

Sequence in context: A092416 A069839 A222192 * A364947 A064456 A347165

Adjacent sequences: A236066 A236067 A236068 * A236070 A236071 A236072

Keyword

nonn

Author

Michel Marcus and Derek Orr, Jan 19 2014

Status

approved