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A308479
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Least k such that k*n and (k+1)*n fail to have a common nonzero digit, or 0 if this property never occurs.
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3
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 4, 1, 2, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 4, 3, 1, 1, 1, 1, 2, 1, 1, 4, 1, 1, 2, 3, 1, 1, 1, 1, 1, 8, 1, 1, 2, 1, 1, 3, 1, 11, 1, 21, 1, 1, 1, 2, 5, 3, 5, 0, 1, 1, 2, 1, 1, 3
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OFFSET
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1,12
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COMMENTS
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a(n) = 0 for the members of A308466.
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LINKS
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FORMULA
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If a(n) = k, then a(10*n) = k.
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EXAMPLE
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a(3) = 1 since 1*3 and 2*3 have no digit in common;
a(12) = 2 since 1*12 and 2*12 have the digit 2 in common, but 2*12 and 3*12 have no nonzero digit in common, thus a(12) = 2;
a(25) = 3 since 1*25 and 2*25 have the digit 5 in common, 2*25 and 3*25 have the digit 5 in common, but 3*25 and 4*25 have no nonzero digit in common; etc.
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MATHEMATICA
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a = Compile[{{n, _Integer}}, Module[{k = 1, id1 = DeleteCases[ IntegerDigits[ n], 0], id2 = DeleteCases[ IntegerDigits[ 2n], 0]}, While[k < 1001 && Intersection[id1, id2] != {}, id1 = id2; k++; id2 = DeleteCases[ Union[ IntegerDigits[(k + 1) n]], 0]]; If[k == 1001, 0, k]]]; Array[a, 198]
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CROSSREFS
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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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