A230029 - OEIS

A230029

Primes p such that f(f(p)) is prime, where f(x) = x^4-x^3-x^2-x-1.

3, 487, 547, 877, 1063, 1291, 1579, 1657, 2287, 2797, 3343, 3793, 4909, 4957, 6163, 6571, 7393, 8461, 8521, 8563, 9631, 11257, 11863, 12211, 12757, 12907, 13063, 13567, 13999, 14983, 15427, 15739, 16087, 16651, 16699, 17419, 17713, 17977

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OFFSET

1,1

LINKS

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

EXAMPLE

3 is prime and (3^4-3^3-3^2-3-1)^4 - (3^4-3^3-3^2-3-1)^3 - (3^4-3^3-3^2-3-1)^2 - (3^4-3^3-3^2-3-1) - 1 = 2755117 is prime. Thus, 3 is a member of this sequence.

PROG

(Python)

import sympy

from sympy import isprime

def f(x):

..return x**4-x**3-x**2-x-1

{print(p) for p in range(10**5) if isprime(p) and isprime(f(f(p)))}

CROSSREFS

Cf. A000040, A237639, A125082.

Sequence in context: A342067 A203681 A195611 * A238447 A241977 A045616

Adjacent sequences: A230026 A230027 A230028 * A230030 A230031 A230032

KEYWORD

nonn

AUTHOR

Derek Orr, Feb 23 2014

STATUS

approved