A381793 Smallest k>1 such that 10*k^(5*2^n)+1 is prime.
6, 11, 649, 792, 1034, 12386, 21813, 87318, 35387, 207339, 67958
Offset: 0
Examples
a(0) = 6, because 10*6^(5*2^0)+1 equals 77761 which is prime.
Programs
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Python
from sympy import isprime from itertools import count def a(n): return next(k for k in count(2) if isprime(k**(5*(2**n)) * 10 + 1))
Extensions
a(7)-a(10) from Michael S. Branicky, Mar 07 2025