

A050695


Composite numbers n such that none of the prime factors of n is a substring of n.


6



4, 6, 8, 9, 10, 14, 16, 18, 21, 27, 34, 38, 40, 44, 46, 48, 49, 51, 54, 56, 57, 58, 60, 64, 66, 68, 69, 74, 76, 78, 80, 81, 84, 86, 87, 88, 90, 91, 94, 96, 98, 99, 100, 104, 106, 108, 111, 114, 116, 117, 118, 119, 121, 129, 133, 134, 136, 140, 141, 143, 144, 146
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OFFSET

1,1


COMMENTS

A131929(a(n)) = 0; together with 1, complement of A131930.  Reinhard Zumkeller, Jul 30 2007


LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10000


EXAMPLE

E.g., 114 = 2*3*19.


MATHEMATICA

d[n_]:=IntegerDigits[n]; t={}; Do[le1=Max@@Length/@(t1=d[First/@FactorInteger[n]]); t2=Flatten[Table[Partition[d[n], i, 1], {i, le1}], 1]; If[!PrimeQ[n]&&Intersection[t1, t2]=={}, AppendTo[t, n]], {n, 2, 146}]; t (* Jayanta Basu, May 31 2013 *)
npfsQ[n_]:=Module[{idn=IntegerDigits[n], f=FactorInteger[n][[All, 1]]}, And@@ Table[SequenceCount[idn, IntegerDigits[f[[i]]]]==0, {i, Length[ f]}]]; Select[Range[200], CompositeQ[#] && npfsQ[#]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 28 2016 *)


CROSSREFS

Cf. A050694, A050696, A035139, A050698.
Sequence in context: A164702 A001745 A276628 * A035139 A316227 A062115
Adjacent sequences: A050692 A050693 A050694 * A050696 A050697 A050698


KEYWORD

nonn,base,nice


AUTHOR

Patrick De Geest, Aug 15 1999


STATUS

approved



