A229708 Least prime of maximal order mod n.

2, 3, 2, 3, 2, 5, 3, 3, 2, 3, 2, 5, 2, 3, 2, 3, 3, 5, 2, 3, 2, 7, 5, 5, 2, 7, 2, 3, 2, 7, 3, 3, 2, 3, 2, 5, 2, 3, 2, 3, 7, 5, 3, 3, 2, 5, 5, 5, 3, 3, 5, 7, 2, 5, 2, 3, 2, 3, 2, 7, 2, 3, 2, 3, 2, 5, 2, 3, 2, 3, 7, 5, 5, 5, 2, 3, 2, 7, 3, 3, 2, 7, 2, 5, 3, 3, 2

Offset: 1

Author

Eric M. Schmidt, Sep 27 2013

Keywords

• nonn
• easy

Comments

a(prime(n)) = A122028(n).

Links

• Eric M. Schmidt, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A111076, A122028.

Programs

Sage

def A229708(n) : m = Integers(n).unit_group_exponent(); return next(p for p in Primes() if n%p != 0 and mod(p,n).multiplicative_order() == m)

Formula

a(n) = A111076(n) if and only if A111076(n) is prime. - Jonathan Sondow, May 17 2017