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%I #10 Mar 30 2012 19:00:28
%S 77,177,268,286,348,355,377,378,384,387,438,446,464,476,477,483,489,
%T 498,535,553,575,628,644,668,674,678,682,686,687,699,717,737,738,746,
%U 747,755,764,767,768,771,772,774,776,777,778,783,786,788,793,826,834,837
%N Composite numbers whose multiplicative persistence is 4.
%C Complement of A046504 with respect to A046513.
%e 77 -> [ 49 ][ 36 ][ 18 ][ 8 ] -> one digit in four steps.
%t persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[1000], ! PrimeQ[#] && persistence[#] == 4 &]
%Y Cf. A046504 (primes whose multiplicative persistence is 4).
%K nonn,base
%O 1,1
%A _Jaroslav Krizek_, Nov 13 2011
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