A319067 a(n) is the least k such that n divides A047994(k) where A047994 is the unitary totient function.

1, 3, 4, 5, 11, 7, 8, 9, 19, 11, 23, 13, 27, 24, 16, 17, 103, 19, 191, 33, 43, 23, 47, 25, 101, 27, 76, 29, 59, 31, 32, 45, 67, 103, 71, 37, 149, 191, 79, 41, 83, 43, 173, 69, 112, 47, 283, 49, 197, 101, 103, 53, 107, 76, 253, 72, 229, 59, 709, 61, 367, 96, 64, 85, 131

Offset: 1

Author

Michel Marcus, Sep 09 2018

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• József Sándor, The Unitary Totient Minimum and Maximum Functions, Studia Universitatis Babes-Bolyai Mathematica, Volume L, Number 2, June 2005.

Crossrefs

Cf. A047994 (unitary totient).

Cf. A005179 (analog for number of divisors), A061026 (analog for Euler totient), A070982 (analog for sum of divisors).

Programs

PARI

a047994(n) = prod(i=1, #n=factor(n)~, n[1, i]^n[2, i]-1);
a(n) = my(k=1); while(a047994(k) % n, k++); k;

Formula

a(p-1) = p for p prime. See Sándor link Theorem 2 p. 95.