A281962 Least k such that k^n - 1 is a totient number (A002202), or 0 if no such k exists.

2, 3, 7, 3, 25, 5, 49, 3, 17, 5, 13, 3, 41, 7, 5, 3, 13, 5, 25, 3, 25, 5, 53, 3, 9, 9, 25, 3, 29, 3, 81, 3, 9, 15, 5, 3, 13, 5, 13, 3, 33, 5, 49, 3, 5, 9, 25, 3, 9, 3, 9, 3, 81, 5, 5, 3, 25, 7, 49, 3, 13, 9, 13, 3, 13, 3

Offset: 1

Author

Altug Alkan, Feb 03 2017

Keywords

• nonn
• more

Examples

			a(5) = 25 because 25^5 - 1 = 5^10 - 1 = 9765624 is a totient number and 25 is the least number with this property.
		

Crossrefs

Cf. A000010, A002202, A045542, A281909.

Programs

PARI

a(n) = my(k=1); while(!istotient(k^n-1), k++); k;

Extensions

a(43)-a(52) from Ray Chandler, Feb 08 2017

a(53)-a(66) from Ray Chandler, Feb 09 2017