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 A063974 Number of terms in inverse set of usigma = sum of unitary divisors = A034448. 3
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,12 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 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 Cf. A051444, A054973, A057637, A034444, A034448. Sequence in context: A002324 A101671 A078979 * A144628 A286604 A217540 Adjacent sequences:  A063971 A063972 A063973 * A063975 A063976 A063977 KEYWORD nonn AUTHOR Labos Elemer, Sep 05 2001 STATUS approved

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Last modified January 29 14:23 EST 2020. Contains 331338 sequences. (Running on oeis4.)