A217351 Numbers k such that 6^k + 7 is prime.
1, 2, 3, 4, 6, 21, 24, 27, 30, 54, 70, 126, 369, 435, 612, 787, 1275, 2155, 2436, 5734, 6016, 16107, 25786, 34266, 38841, 45834, 46584
Offset: 1
Programs
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Mathematica
Select[Range[10000], PrimeQ[6^# + 7] &]
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PARI
is(n)=ispseudoprime(6^n+7) \\ Charles R Greathouse IV, Jun 13 2017
Extensions
a(20)-a(21) from Bruno Berselli, Oct 04 2012
a(22)-a(23) from Michael S. Branicky, Apr 30 2023
a(24)-a(27) from Michael S. Branicky, Sep 19 2024