A265484 Numbers k such that 36^k - 6^k - 1 is prime.
1, 2, 3, 4, 24, 63, 81, 92, 165, 232, 236, 591, 669, 1343, 2973, 3630, 5600, 7019, 17169, 31945, 52172
Offset: 1
Examples
4 is in the sequence because 36^4 - 6^4 - 1 = 1678319 is prime.
Crossrefs
Cf. similar sequences listed in A265481.
Programs
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Magma
[n: n in [0..300] | IsPrime(36^n-6^n-1)];
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Mathematica
Select[Range[1000], PrimeQ[36^# - 6^# - 1] &]
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PARI
for(n=1, 1e3, if(ispseudoprime(36^n - 6^n - 1), print1(n, ", "))) \\ Altug Alkan, Dec 12 2015
Extensions
a(14)-a(18) from Ray Chandler, Sep 25 2019
a(18) corrected and a(19)-a(21) added by Robert Price, Jan 06 2020
Comments