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A068189
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Smallest positive number whose product of digits equals n, or a(n)=0 if no such number exists, e.g. when n has prime-factor larger than 7.
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12
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1, 2, 3, 4, 5, 6, 7, 8, 9, 25, 0, 26, 0, 27, 35, 28, 0, 29, 0, 45, 37, 0, 0, 38, 55, 0, 39, 47, 0, 56, 0, 48, 0, 0, 57, 49, 0, 0, 0, 58, 0, 67, 0, 0, 59, 0, 0, 68, 77, 255, 0, 0, 0, 69, 0, 78, 0, 0, 0, 256, 0, 0, 79, 88, 0, 0, 0, 0, 0, 257, 0, 89, 0, 0, 355, 0, 0, 0, 0, 258, 99, 0, 0, 267, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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EXAMPLE
| n=2,10,50,250 gives a(n)=2,25,255,2555; n=11,39,78, etc..a(n)=0.
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MATHEMATICA
| f[x_] := Apply[Times, IntegerDigits[x]] a = Table[0, {256} ]; Do[ b = f[n]; If[b < 257 && a[[b]] == 0, a[[b]] =n], {n, 1, 10000} ]; a
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PROG
| (Python) [From Dmitry Kamenetsky (dkamen(AT)rsise.anu.edu.au), Oct 20 2008]
.def convert(n):
..if (n==1): return 1
..result=0
..cur=1
..while(n>1):
...found=False
...for i in range(9, 1, -1):
....if (n%i==0):
.....result+=(cur*i)
.....cur*=10
.....n/=i
.....found=True
.....break
..
....if (not found): return 0
..
..return result
..
..
.N=256
.for n in range(1, N):
..print n, convert(n)
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CROSSREFS
| Cf. A001222, A002473, A067734, A068183-A068187, A068189-A068191.
Cf. A085123.
Sequence in context: A134703 A061862 A007532 * A069716 A095289 A174141
Adjacent sequences: A068186 A068187 A068188 * A068190 A068191 A068192
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KEYWORD
| base,nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Feb 19 2002
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