A272345 Numbers n such that 8^n-7^(n-1) is prime.

1, 3, 5, 29, 41, 83, 471, 725, 1277, 10271, 15069, 97731

Offset: 1

Author

Robert Price, Apr 26 2016

Keywords

• nonn
• more

Comments

a(13) > 10^5.

Examples

			5 is a member since 8^5 - 7^4 = 32768 - 2401 = 30367 which is a prime number.
		

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884.

Programs

Mathematica

Select[Range[0, 100000], PrimeQ[8^# - 7^(# - 1)] &]

PARI

is(n)=ispseudoprime(8^n-7^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017