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 A327054 a(n) is the smallest number m such that the antiharmonic mean of the divisors is n, or 0 if no such m exists. 0
 1, 0, 4, 0, 0, 0, 9, 0, 0, 0, 16, 0, 20, 0, 0, 0, 0, 0, 0, 0, 25, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 50, 0, 0, 0, 0, 0, 0, 0, 49, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 81, 0, 100, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 144, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) = the smallest number m such that sigma_2(n) / sigma_1(n) = A001157(m) / A000203(m) = n, or 0 if no such m exists. Zeros occur if n is not in A176799. See A000290, A091911 and A162538 for like sequences for geometric, arithmetic and harmonic means of the divisors. LINKS EXAMPLE a(3) = 4 because 4 is the smallest number m with sigma_2(m) / sigma_1(m) = 3; sigma_2(4) / sigma_1(4) = 21 / 7 = 3. PROG (MAGMA) A372054:=func; [A372054(n): n in[1..100]] CROSSREFS Cf. A020487, A176797, A176799, A176800. Sequence in context: A003194 A286875 A105570 * A101419 A060278 A046770 Adjacent sequences:  A327051 A327052 A327053 * A327055 A327056 A327057 KEYWORD nonn AUTHOR Jaroslav Krizek, Oct 06 2019 STATUS approved

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Last modified June 5 18:48 EDT 2020. Contains 334854 sequences. (Running on oeis4.)