A239505 Numbers n such that n^9+9 and n^9-9 are prime.

2, 1642, 2870, 2948, 4238, 5480, 5920, 7502, 8210, 8248, 9328, 11572, 13538, 13610, 14818, 14908, 19298, 21022, 21890, 21988, 22340, 23000, 23252, 26282, 26380, 29168, 31660, 32602, 33338, 33650, 36220, 38248, 38422, 43490, 43910, 44948, 45188, 46048

Offset: 1

Author

Derek Orr, Mar 20 2014

Keywords

• nonn

Comments

All numbers in this sequence are even.

Intersection of A239346 and A239417.

Examples

			2^9+9 = 521 is prime and 2^9-9 = 503 is prime. Thus, 2 is a member of this sequence.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A239346, A239417.

Programs

Mathematica

Select[Range[50000],AllTrue[#^9+{9,-9},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Feb 12 2015 *)

Python

import sympy
from sympy import isprime
def TwoBoth(x):
  for k in range(10**6):
    if isprime(k**x+x) and isprime(k**x-x):
      print(k)
TwoBoth(9)