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A242557
Least number k such that n^128+k^128 is prime.
1
1, 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, 20, 209, 606, 1529, 32, 31, 1094, 139, 754, 647, 38, 37, 262, 69, 94, 631, 90, 25, 38, 195, 10, 277, 232, 187, 554, 189, 10, 47, 216, 131, 1132, 173, 390
OFFSET
1,2
COMMENTS
If a(n) = 1, then n is in A056994.
MATHEMATICA
lnk[n_]:=Module[{c=n^128, k}, k=If[EvenQ[c], 1, 2]; While[!PrimeQ[c+ k^128], k = k+2]; k]; Join[{1}, Array[lnk, 60, 2]] (* Harvey P. Dale, Mar 17 2015 *)
PROG
(Python)
import sympy
from sympy import isprime
def a(n):
for k in range(10**4):
if isprime(n**128+k**128):
return k
n = 1
while n < 100:
print(a(n))
n += 1
(PARI) a(n)=for(k=1, 10^4, if(ispseudoprime(n^128+k^128), return(k)));
n=1; while(n<100, print(a(n)); n+=1)
CROSSREFS
Sequence in context: A115486 A157885 A204377 * A345072 A214503 A054033
KEYWORD
nonn
AUTHOR
Derek Orr, May 17 2014
STATUS
approved