login
A327164
Number of iterations of x -> gcd(usigma(x),x) needed to reach a fixed point, where usigma is the sum of unitary divisors of n (A034448).
3
0, 1, 1, 1, 1, 0, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 1, 1, 3, 1, 2, 1, 3, 1, 2, 1, 2, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 3, 2, 1, 2, 1, 2, 2, 2, 1, 1, 1, 2, 1, 2, 1, 0, 1, 2, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 0, 2, 2, 1, 2, 2, 3, 1, 2, 2, 3, 1, 1, 1, 2, 2
OFFSET
1,10
PROG
(PARI)
A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448
A323166(n) = gcd(n, A034448(n));
A327164(n) = { my(u=A323166(n)); if(u==n, 0, 1+A327164(u)); }
CROSSREFS
Cf. A034448, A323166, A327158 (positions of zeros).
Cf. also A326194.
Sequence in context: A243906 A100889 A206828 * A094781 A023582 A306717
KEYWORD
nonn
AUTHOR
Antti Karttunen, Aug 28 2019
STATUS
approved