A244950 Least number k > n such that k^128 + n^128 is prime.

120, 113, 106, 259, 304, 85, 212, 135, 158, 47, 62, 985, 84, 47, 518, 485, 178, 169, 106, 27, 88, 139, 632, 47, 44, 643, 194, 209, 606, 1529, 32, 113, 1094, 139, 754, 647, 38, 45, 262, 69, 94, 631, 90, 527, 326, 195, 54, 277, 232, 187, 554, 189, 78, 799, 216, 131, 1132, 173

Offset: 1

Author

Derek Orr, Jul 08 2014

Keywords

• nonn

Comments

a(n) = n+1 iff n is in A215431.

Examples

			The n-value for which n^128 + 1 is prime (sequence A056994) is n = 120 (where n > 1 by definition). Thus a(1) = 120.
		

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A158979, A089489, A242557.

Programs

Mathematica

lnk[n_]:=Module[{k=n+1,n128=n^128},While[!PrimeQ[n128+k^128],k++];k]; Array[lnk,60] (* Harvey P. Dale, Apr 22 2018 *)

PARI

a(n)=for(k=n+1,10^4,if(isprime(k^128+n^128),return(k)))
n=1;while(n<100,print1(a(n),", ");n++)

Python

import sympy
from sympy import isprime
def a(n):
    for k in range(n+1,10**4):
        if isprime(k**128+n**128):
            return k
for n in range(1, 100):
    print(a(n), end=', ')