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A199995 Composite numbers whose multiplicative persistence is 5. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Complement of A046505 with respect to A046514.
LINKS
EXAMPLE
679 -> [ 378 ][ 168 ][ 48 ][ 32 ][ 6 ] -> one digit in five steps.
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 *)
CROSSREFS
Cf. A046505 (primes whose multiplicative persistence is 5).
Sequence in context: A097771 A121105 A046514 * A352263 A340091 A164650
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Nov 13 2011
STATUS
approved

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Last modified May 26 00:55 EDT 2024. Contains 372806 sequences. (Running on oeis4.)