A273524 Numbers n such that 7^n-6^(n-1) is prime.

2, 3, 5, 6, 7, 11, 17, 18, 54, 509, 529, 2526, 3042, 3421, 4485, 13127, 17602, 23825, 27381

Offset: 1

Author

Robert Price, May 23 2016

Keywords

• nonn
• more

Comments

a(20) > 10^5.

Crossrefs

Cf. A093713, A093765.

Programs

Mathematica

Select[Range[0, 100000], PrimeQ[7^# - 6^(# - 1)] &]

PARI

is(n)=ispseudoprime(7^n-6^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017