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A064023
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Smallest prime m such that prod(m)=n*l(m)*sum(m) where prod(m) is the product of the digits of m, l(m) is the number of digits of m, sum(m) is the sum of the digits of m; or 0 if no such m exists.
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1
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2, 347, 5861, 225461, 55541, 4583, 4457, 117883, 15559, 151687, 0, 155383, 0, 5857, 118589, 126487, 0, 4789, 0, 134587, 7687, 0, 0, 25867, 165457, 0, 34759, 182687, 0, 38557, 0, 44587, 0, 0, 45757, 25889, 0, 0, 0, 244567, 0, 148667, 0, 0, 225689, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| If n is divisible by a prime larger than 7, then n can't divide prod(m), so a(n)=0. Are there any other values of n with a(n)=0?
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EXAMPLE
| a(2)=347 because prod(347)=84, sum(347)=14, l(347)=3, n=2 and 84=2*3*14
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MATHEMATICA
| id := IntegerDigits; prod[n_] := Times@@id[n]; l[n_] := Length[id[n]]; sum[n_] := Plus@@id[n]; a[n_] := If[FactorInteger[2n][[ -1, 1]]>7, 0, For[k=1, True, k++, m=Prime[k]; If[prod[m]==n*l[m]sum[m], Return[m]]]]
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CROSSREFS
| Cf. A064022.
Sequence in context: A172136 A064501 A063831 * A179959 A024350 A012669
Adjacent sequences: A064020 A064021 A064022 * A064024 A064025 A064026
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KEYWORD
| nonn,base
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AUTHOR
| Felice Russo (frusso(AT)micron.com), Sep 18 2001
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EXTENSIONS
| Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jun 02 2002
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