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Search: id:A064022
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| A064022 |
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Smallest value of 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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+0
2
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| 1, 88, 369, 666, 579, 1899, 789, 2688, 999, 3588, 0, 4668, 0, 3789, 4599, 4689, 0, 4789, 0, 5788, 6778, 0, 0, 5889, 35559, 0, 25599, 35667, 0, 35578, 0, 8888, 0, 0, 45577, 25889, 0, 0, 0, 145688, 0, 45579, 0, 0, 55569, 0, 0, 35888, 55677, 245559, 0, 0
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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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
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a(2)=88 because prod(88)=64, sum(88)=16, l(88)=2, n=2 and 64=2*2*16
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MATHEMATICA
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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[m=1, True, m++, If[prod[m]==n*l[m]sum[m], Return[m]]]]
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CROSSREFS
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Cf. A064023.
Sequence in context: A046330 A001347 A003782 this_sequence A116065 A052049 A046378
Adjacent sequences: A064019 A064020 A064021 this_sequence A064023 A064024 A064025
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KEYWORD
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nonn,base
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AUTHOR
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Felice Russo (felice.russo(AT)katamail.com), Sep 18 2001
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EXTENSIONS
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Corrected by Larry Reeves (larryr(AT)acm.org), Sep 20 2001
Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Jun 02 2002
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