A363375 Numbers k such that 3^(k-1) - 2^k is prime.

4, 6, 7, 8, 22, 32, 45, 52, 58, 60, 85, 98, 211, 290, 291, 426, 428, 712, 903, 1392, 1683, 1828, 2342, 3482, 4818, 4887, 9060, 14328, 16948, 17581, 18358, 65298, 69237, 84770, 94788

Offset: 1

Author

Sébastien Tao, May 29 2023

Keywords

• nonn
• hard
• more

Comments

a(36) > 100000. - Hugo Pfoertner, Jun 03 2023

Examples

			a(1) = 4 is in the sequence because 3^3 - 2^4 =  11 is prime.
a(2) = 6 is in the sequence because 3^5 - 2^6 = 179 is prime.
		

Crossrefs

Cf. A057468, A162714, A363024.

The sequence that results from increasing all terms by 1 in A162714 is a subsequence.

Programs

Mathematica

Cases[Range[1, 300], k_ /; PrimeQ[3^(k - 1) - 2^k]]

Extensions

a(16)-a(31) from Michael S. Branicky, May 29 2023

a(32)-a(33) from Hugo Pfoertner, May 29 2023

a(34)-a(35) from Hugo Pfoertner, Jun 02 2023