A035140 Digits of juxtaposition of prime factors of composite n appear also in n.

25, 32, 121, 125, 128, 132, 135, 143, 175, 187, 243, 250, 256, 295, 312, 324, 341, 351, 375, 432, 451, 512, 625, 671, 679, 735, 781, 875, 928, 932, 1023, 1024, 1053, 1057, 1207, 1243, 1250, 1255, 1324, 1325, 1328, 1331, 1352, 1359, 1372, 1375, 1377, 1379

Offset: 1

Author

Patrick De Geest, Nov 15 1998

Keywords

• nonn
• base

Examples

			295 = 5 * 59 since {5,9} is a subset of {2,5,9}.
		

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A035139, A035141.

Programs

Mathematica

id[n_]:=Complement[Range[0,9],IntegerDigits[n]]; fac[n_]:=Flatten[IntegerDigits[Take[FactorInteger[n],All,1]]]; t={}; Do[If[!PrimeQ[n] && Intersection[id[n],fac[n]] == {}, AppendTo[t,n]], {n,2,1380}]; t (* Jayanta Basu, May 01 2013 *)
Select[Range@10000, CompositeQ@# && SubsetQ[IntegerDigits@#,Flatten@IntegerDigits@(#[[1]] & /@ FactorInteger@#)] &] (* Hans Rudolf Widmer, May 11 2023 *)

Python

from sympy import factorint, isprime
def ok(n): return n > 1 and not isprime(n) and set("".join(str(p) for p in factorint(n))) <= set(str(n))
print([k for k in range(1380) if ok(k)]) # Michael S. Branicky, May 11 2023

Extensions

Name clarified by Hans Rudolf Widmer, May 11 2023