A152178 Smallest prime factor of G-n, where G is any sufficiently large power tower of 3, e.g., Graham's number.

3, 2, 5, 2, 107, 2, 3, 2, 101, 2, 29, 2, 3, 2, 13, 2, 3626257, 2, 3, 2, 7, 2, 5, 2, 3, 2, 1511, 2, 173, 2, 3, 2, 5, 2, 7, 2, 3, 2, 197, 2, 13, 2, 3, 2, 17491, 2, 18540593, 2, 3, 2, 53, 2, 5, 2, 3, 2, 19, 2, 17, 2, 3, 2, 5, 2, 11, 2, 3, 2, 29, 2, 97, 2, 3, 2, 251

Offset: 0

Author

Karl W. Heuer, Nov 28 2008

Keywords

• nonn

Comments

Least prime p such that A240162(p) == n (mod p). - Jinyuan Wang, Aug 30 2020

Examples

			a(2) = 5 because 3^3^3^... - 2 = 0 (mod 5).
		

Links

• Jinyuan Wang, Table of n, a(n) for n = 0..100
• Wikipedia, Graham's number

Crossrefs

Cf. A152177, A240162.