A050696 At least one prime factor of composite a(n) is a substring of a(n).

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

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: A154390 A346608 A156683 * A144266 A162826 A162820

Adjacent sequences: A050693 A050694 A050695 * A050697 A050698 A050699

Keyword

nonn,base

Author

Patrick De Geest, Aug 15 1999

Status

approved