A242554 Least number k such that n^16 + k^16 is prime.

1, 1, 4, 3, 6, 5, 6, 7, 22, 13, 16, 5, 8, 5, 14, 11, 10, 7, 16, 31, 8, 9, 10, 11, 38, 29, 10, 9, 22, 61, 20, 5, 4, 3, 16, 11, 6, 25, 28, 7, 6, 17, 16, 1, 46, 9, 58, 61, 22, 41, 92, 3, 14, 19, 14, 23, 56, 37, 20, 109, 6, 121, 10, 39, 4, 67, 34, 11, 26, 9, 30, 11, 12, 1

Offset: 1

Author

Derek Orr, May 17 2014

Keywords

• nonn

Comments

If a(n) = 1, then n is in A006313.

Examples

			4^16+1^16 = 4294967297 is not prime. 4^16+2^16 = 4295032832 is not prime. 4^16+3^16 = 4338014017 is prime. Thus, a(4) = 3.
		

Crossrefs

Cf. A069003, A006313.

Programs

PARI

a(n)=for(k=1,oo,if(ispseudoprime(n^16+k^16),return(k)));

Python

import sympy
from sympy import isprime
def a(n):
  for k in range(10**4):
    if isprime(n**16+k**16):
      return k
n = 1
while n < 100:
  print(a(n))
  n += 1