A067006 Smallest number for which the totient is divisible by the n-th nontotient number, that is, the n-th term of A007617.

7, 11, 29, 19, 23, 53, 29, 31, 103, 191, 43, 47, 101, 53, 81, 59, 311, 67, 103, 71, 149, 191, 79, 83, 173, 181, 283, 197, 101, 103, 107, 121, 229, 709, 367, 311, 127, 131, 269, 137, 139, 569, 293, 149, 151, 229, 463, 317, 163, 167, 1021, 173, 349, 179, 181, 547

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = min_{x : mod(phi(x), A007617(n)) = 0}. For all nontotient numbers x, q*x+1 is prime with large enough q and a divisor of phi(q*x+1) = q*x is x, the selected nontotient number. [Corrected by Sean A. Irvine, Nov 28 2023]

Example

14 = A007617(7) is not totient of any other number, but phi(29) = 28 is divisible by 14 and 29 is the smallest number of which the totient is a multiple of 14, so a(7)=29.

Crossrefs

Cf. A000010, A007617, A066674, A066675, A066676, A066677, A066678, A067005.

Sequence in context: A158807 A377971 A338929 * A136020 A356467 A076304

Adjacent sequences: A067003 A067004 A067005 * A067007 A067008 A067009

Keyword

nonn

Author

Labos Elemer, Dec 22 2001

Status

approved