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

1,1

Comments

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

Links

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

Example

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

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 *)

Prog

(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=', ')
(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++)

Crossrefs

Cf. A158979, A089489, A242557.

Sequence in context: A051727 A174867 A332417 * A174149 A268920 A332560

Adjacent sequences: A244947 A244948 A244949 * A244951 A244952 A244953

Keyword

nonn

Author

Derek Orr, Jul 08 2014

Status

approved