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

1,1

Links

Table of n, a(n) for n=1..42.

Example

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.

Sequence in context: A027672 A322138 A104138 * A083809 A092967 A056431

Adjacent sequences: A281906 A281907 A281908 * A281910 A281911 A281912

Keyword

nonn,more

Author

Altug Alkan, Feb 01 2017

Extensions

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

Status

approved