A281909 Smallest k such that k^i - 1 is a totient number (A002202) for all i = 1 to n, or 0 if no such k exists.

2, 3, 7, 7, 25, 25, 49, 49, 49, 49, 49, 49, 81, 81, 81, 81, 241, 241, 289, 289, 289, 289, 289, 289, 289, 289, 289, 289, 289, 289, 721, 721, 721, 721, 721, 721, 961, 961, 961, 961, 961, 961

Offset: 1

Author

Altug Alkan, Feb 01 2017

Keywords

• nonn
• more

Examples

			a(3) = 7 because 7 - 1 = 6, 7^2 - 1 = 48, 7^3 - 1 = 342 are all totient numbers and 7 is the least number with this property.
		

Crossrefs

Cf. A000010, A002202, A045542.

Extensions

a(18)-a(42) from Max Alekseyev, Feb 07 2017, Mar 06 2017