A046506 -id:A046506 - cp's OEIS frontend

A046515 Numbers with multiplicative persistence value 6.

6788, 6878, 6887, 7688, 7868, 7886, 8678, 8687, 8768, 8786, 8867, 8876, 16788, 16878, 16887, 17688, 17868, 17886, 18678, 18687, 18768, 18786, 18867, 18876, 23788, 23878, 23887, 24678, 24687, 24768, 24786, 24867, 24876, 26478, 26487

Offset: 1

Patrick De Geest, Sep 15 1998

			6788 -> [ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in six steps.

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

Cf. A003001, A014120, A046506.

mp:= proc(n) option remember;
    if n <= 9 then return 0 fi;
    1+procname(convert(convert(n,base,10),`*`))
end proc:
select(mp=6, [$1..30000]); # Robert Israel, Feb 12 2019

Offset corrected by Robert Israel, Feb 12 2019

A199996 Composite numbers whose multiplicative persistence is 6.

Original entry on oeis.org

6788, 6878, 6887, 7688, 7868, 7886, 8678, 8687, 8768, 8786, 8876, 16788, 16878, 16887, 17688, 17868, 17886, 18678, 18687, 18768, 18786, 18867, 18876, 23788, 23878, 24678, 24687, 24768, 24786, 24867, 24876, 26478, 26487, 26748, 26784, 26847, 26874, 27388

Offset: 1

Jaroslav Krizek, Nov 13 2011

Complement of A046506 with respect to A046515.

			6788 -> [ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in six steps.

Cf. A046506 (primes whose multiplicative persistence is 6).

persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[30000], ! PrimeQ[#] && persistence[#] == 6 &] (* T. D. Noe, Nov 23 2011 *)

cp's OEIS Frontend

A046515 Numbers with multiplicative persistence value 6.

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