login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A319067
a(n) is the least k such that n divides A047994(k) where A047994 is the unitary totient function.
1
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
1,2
LINKS
József Sándor, The Unitary Totient Minimum and Maximum Functions, Studia Universitatis Babes-Bolyai Mathematica, Volume L, Number 2, June 2005.
FORMULA
a(p-1) = p for p prime. See Sándor link Theorem 2 p. 95.
PROG
(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;
CROSSREFS
Cf. A047994 (unitary totient).
Cf. A005179 (analog for number of divisors), A061026 (analog for Euler totient), A070982 (analog for sum of divisors).
Sequence in context: A225906 A332790 A329524 * A224503 A349005 A128920
KEYWORD
nonn
AUTHOR
Michel Marcus, Sep 09 2018
STATUS
approved