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 A307823 The number of nonunitary abundant numbers below 10^n. 5
 0, 5, 75, 812, 8079, 81052, 808477, 8097357, 80939927, 809350234 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA Conjecture: Lim_{n->oo} a(n)/10^n =  0.0809... is the density of nonunitary abundant numbers. EXAMPLE Below 10^2 there are 5 nonunitary abundant numbers, 36, 48, 72, 80, and 96, thus a(2) = 5. MATHEMATICA usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); nusigma[n_] := DivisorSigma[1, n] - usigma[n]; c = 0; k = 1; seq={}; Do[ While[ k < 10^n, If[ nusigma[k]>k, c++ ]; k ++]; AppendTo[seq, c], {n, 1, 5}]; seq CROSSREFS Cf. A048146, A064597, A302992, A302993, A302994, A307820, A307821. Sequence in context: A127212 A091903 A105490 * A105494 A030986 A284924 Adjacent sequences:  A307820 A307821 A307822 * A307824 A307825 A307826 KEYWORD nonn,more AUTHOR Amiram Eldar, Apr 30 2019 STATUS approved

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Last modified August 14 12:15 EDT 2022. Contains 356116 sequences. (Running on oeis4.)