A063974 Number of terms in inverse set of usigma = sum of unitary divisors = A034448.

1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 0, 2, 0, 1, 0, 0, 1, 2, 0, 2, 0, 0, 0, 3, 0, 1, 0, 1, 0, 3, 0, 2, 1, 0, 0, 2, 0, 1, 0, 1, 0, 2, 0, 1, 0, 0, 0, 3, 0, 2, 0, 0, 0, 3, 0, 1, 0, 0, 0, 4, 0, 1, 0, 0, 1, 0, 0, 2, 0, 1, 0, 6, 0, 1, 0, 0, 0, 1, 0, 3, 0, 1, 0, 3, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 4, 0, 1, 0, 1, 0, 2, 0, 2, 0

Offset

1,12

Links

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

Formula

Size of set {x; usigma(x) = n}.

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = A308041. - Amiram Eldar, Dec 23 2024

Example

usigma(x) = 288, invusigma(288) = {138,154,165,168,213,235,248,253}, so a(288) = 8, the number of all terms in the inverse set.

Crossrefs

Cf. A034444, A034448, A051444, A054973, A057637, A308041.

Sequence in context: A101671 A333325 A078979 * A144628 A373832 A286604

Adjacent sequences: A063971 A063972 A063973 * A063975 A063976 A063977

Keyword

nonn

Author

Labos Elemer, Sep 05 2001

Status

approved