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 A302993 Number of unitary abundant numbers < 10^n. 0
 0, 5, 64, 691, 7011, 70030, 699597, 7005450, 70048740, 700321813, 7003128054, 70034216605, 700350142296, 7003426996800, 70033987968599, 700341098675985, 7003416399263312 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA Conjecture: Lim_{n->oo} a(n)/10^n = 0.07... is the density of unitary abundant numbers. MATHEMATICA usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; uabQ[n_] := usigma[n] > 2 n; c = 0; k = 1; seq={}; Do[While[k < 10^n, If[uabQ[k], c++]; k++]; AppendTo[seq, c], {n, 1, 5}]; seq CROSSREFS Cf. A034448, A034683, A302992. Sequence in context: A222455 A178295 A054937 * A266095 A255523 A193222 Adjacent sequences:  A302990 A302991 A302992 * A302994 A302995 A302996 KEYWORD nonn,more AUTHOR Amiram Eldar, Apr 17 2018 EXTENSIONS a(10)-a(17) from Hiroaki Yamanouchi, Aug 03 2018 STATUS approved

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Last modified December 17 04:31 EST 2018. Contains 318192 sequences. (Running on oeis4.)