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%I #9 Aug 03 2014 14:01:36
%S 68889,68898,68988,69888,86889,86898,86988,88689,88698,88869,88896,
%T 88968,88986,89688,89868,89886,96888,98688,98868,98886,168889,168898,
%U 168988,169888,186898,186988,188689,188698,188896,188968,188986,189688,189868,189886,196888
%N Composite numbers whose multiplicative persistence is 7.
%C Complement of A046507 with respect to A046516.
%e 68889 -> [ 27648 ][ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in seven steps.
%t persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[300000], ! PrimeQ[#] && persistence[#] == 7 &] (* _T. D. Noe_, Nov 23 2011 *)
%Y Cf. A046507 (primes whose multiplicative persistence is 7).
%K nonn,base
%O 1,1
%A _Jaroslav Krizek_, Nov 13 2011
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