A366323 Numbers k such that (k*3^k - 1)/2 is a prime.

5, 25, 125, 389, 549, 1125, 12889, 26925

Offset: 1

Author

Jon E. Schoenfield, Oct 06 2023

Keywords

• nonn
• hard
• more

Comments

Odd terms of A242274.

Examples

			k = 5 is a term: (5*3^5 - 1)/2 = 607 is a prime.
		

Crossrefs

Cf. A242274.

Extensions

a(8) from Michael S. Branicky, Oct 08 2024