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

Author

Patrick De Geest, Aug 15 1999

Keywords

• nonn
• base

Examples

			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.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..4720

Crossrefs

Cf. A050694, A050695.

Programs

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 *)