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(Python)
from sympy import isprime
def a(n):
if n > 1 and n%3 == 1: return 0
k = 2
while not isprime(n**k + n + 1): k += 1
return k
print([a(n) for n in range(1, 96)]) # Michael S. Branicky, Jul 08 2021
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Robert Israel, <a href="/A346149/b346149.txt">Table of n, a(n) for n = 1..212</a>
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(PARI) a(n) = if ((n>1) && ((n%3)==1), 0, my(k=2); while (!isprime(n^k+n+1), k++); k); \\ Michel Marcus, Jul 07 2021
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