A046505 -id:A046505 - cp's OEIS frontend

A046514 Numbers with multiplicative persistence value 5.

679, 688, 697, 769, 796, 868, 886, 967, 976, 1679, 1688, 1697, 1769, 1796, 1868, 1886, 1967, 1976, 2379, 2388, 2397, 2468, 2486, 2648, 2684, 2688, 2739, 2777, 2793, 2838, 2846, 2864, 2868, 2883, 2886, 2937, 2973, 3279, 3288, 3297, 3367, 3376, 3448

Offset: 1

Patrick De Geest, Sep 15 1998

			2777 -> [ 686 ][ 288 ][ 128 ][ 16 ][ 6 ] -> one digit in five steps.

Robert Israel, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Multiplicative Persistence

Cf. A003001, A014120, A046505.

mp:= proc(n) option remember;
    if n <= 9 then return 0 fi;
    1+procname(convert(convert(n,base,10),`*`))
end proc:
select(mp=5, [$1..4000]); # Robert Israel, Feb 12 2019

Offset corrected by Robert Israel, Feb 12 2019

A199995 Composite numbers whose multiplicative persistence is 5.

Original entry on oeis.org

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

Jaroslav Krizek, Nov 13 2011

Complement of A046505 with respect to A046514.

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

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

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

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 *)

cp's OEIS Frontend

A046514 Numbers with multiplicative persistence value 5.

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