A199995 Composite numbers whose multiplicative persistence is 5.

679, 688, 697, 796, 868, 886, 976, 1679, 1688, 1769, 1796, 1868, 1886, 1967, 1976, 2379, 2388, 2397, 2468, 2486, 2648, 2684, 2688, 2739, 2793, 2838, 2846, 2864, 2868, 2883, 2886, 2937, 2973, 3279, 3288, 3297, 3367, 3376, 3448, 3484, 3488, 3729, 3736, 3763

Offset: 1

Author

Jaroslav Krizek, Nov 13 2011

Keywords

• nonn
• base

Comments

Complement of A046505 with respect to A046514.

Examples

			679 -> [ 378 ][ 168 ][ 48 ][ 32 ][ 6 ] -> one digit in five steps.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A046505 (primes whose multiplicative persistence is 5).

Programs

Mathematica

persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[4000], !PrimeQ[#] && persistence[#] == 5 &] (* T. D. Noe, Nov 23 2011 *)
mp5Q[n_]:=CompositeQ[n]&&Length[NestWhileList[ Times@@IntegerDigits[ #]&,n,#>9&]] == 6; Select[Range[4000],mp5Q] (* Harvey P. Dale, Apr 23 2022 *)