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A199996
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Composite numbers whose multiplicative persistence is 6.
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0
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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
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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6788 -> [ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in six steps.
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MATHEMATICA
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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 *)
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CROSSREFS
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Cf. A046506 (primes whose multiplicative persistence is 6).
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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