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 A108780 Numbers n such that (n / sum of digits of n) is a golden semiprime. 2
 54, 135, 1122, 1386, 2244, 2805, 3366, 3927, 4488, 5301, 12369, 15318, 20445, 22977, 24534, 28623, 44979, 58941, 74169, 78588, 98892, 131454, 153363, 175272, 197181, 210693, 213206, 222132, 240792, 240999, 270891, 274122, 304580, 335038, 350267 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..2595 (terms below 10^11) EXAMPLE 1122 is a term because 1122/6=187 and 187=11*17 and 11*phi-17 = 0.798373... < 1. MATHEMATICA goldQ[n_] := Module[{f = FactorInteger[n]}, If[Length[f] != 2, False, If[Max[f[[;; , 2]]] != 1, False, Abs[f[[2, 1]] - f[[1, 1]] * GoldenRatio] < 1]]]; sumDigits[n_] := Plus @@ IntegerDigits[n]; seqQ[n_] := Divisible[n, (sd = sumDigits[n])] && goldQ[n/sd]; Select[Range[360000], seqQ] (* Amiram Eldar, Nov 29 2019 *) CROSSREFS Cf. A001101, A108540. Sequence in context: A184067 A044305 A044686 * A057396 A286836 A304172 Adjacent sequences:  A108777 A108778 A108779 * A108781 A108782 A108783 KEYWORD base,nonn AUTHOR Jason Earls, Jun 26 2005 STATUS approved

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Last modified May 31 22:45 EDT 2020. Contains 334756 sequences. (Running on oeis4.)