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A063974
Number of terms in inverse set of usigma = sum of unitary divisors = A034448.
7
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
FORMULA
Size of set {x; usigma(x)=n}.
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
KEYWORD
nonn
AUTHOR
Labos Elemer, Sep 05 2001
STATUS
approved