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A039938
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Smallest k for which k, 2k, ... nk all contain the digit 7.
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12
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7, 37, 237, 1789, 4357, 14379, 19587, 93957, 189572, 189572, 189597, 189597, 189597, 1234397, 1839597, 1958798, 1983957, 1983957, 1983957, 1983957, 1983957, 1983957, 3978594, 11983957, 19596487, 29195397, 29195397, 29195397
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(2)=37 since 37 and 74 contain a 7.
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MATHEMATICA
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Table[SelectFirst[Range[10^6], Times @@ Boole@ Map[DigitCount[#, 10, 7] > 0 &, # Range@ n] > 0 &], {n, 12}] (* Michael De Vlieger, Apr 27 2017, Version 10 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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