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 A050696 At least one prime factor of composite a(n) is a substring of a(n). 4
 12, 15, 20, 22, 24, 25, 26, 28, 30, 32, 33, 35, 36, 39, 42, 45, 50, 52, 55, 62, 63, 65, 70, 72, 75, 77, 82, 85, 92, 93, 95, 102, 105, 110, 112, 115, 120, 122, 123, 124, 125, 126, 128, 130, 132, 135, 138, 142, 145, 147, 150, 152, 153, 155, 162, 165, 170, 172, 175 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..4720 EXAMPLE 26 is in the sequence because 26 = 2 * 13 and the factor 2 appears in the decimal representation. Though 13 does not appear, the 2 is enough for 26 to be in the sequence. 27 is not in the sequence since 27 = 3 * 3 * 3, which does not appear in the decimal representation. MATHEMATICA digs[n_] := IntegerDigits[n]; A050696 = {}; Do[le1 = Max@@Length/@(prFDigs = digs[First/@FactorInteger[n]]); dSubStrs = Flatten[Table[Partition[digs[n], i, 1], {i, le1}], 1]; If[!PrimeQ[n] && Intersection[prFDigs, dSubStrs] != {}, AppendTo[A050696, n]], {n, 2, 180}]; A050696 (* Jayanta Basu, May 31 2013 *) CROSSREFS Cf. A050694, A050695. Sequence in context: A117815 A154390 A156683 * A144266 A162826 A162820 Adjacent sequences:  A050693 A050694 A050695 * A050697 A050698 A050699 KEYWORD nonn,base AUTHOR Patrick De Geest, Aug 15 1999 STATUS approved

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Last modified September 22 21:07 EDT 2020. Contains 337291 sequences. (Running on oeis4.)