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A096683
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Least k such that decimal representation of k*n contains only digits 0 and 4.
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2
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4, 2, 148, 1, 8, 74, 572, 5, 49382716, 4, 4, 37, 308, 286, 296, 25, 2612, 24691358, 2316, 2, 1924, 2, 19148, 185, 16, 154, 163127572, 143, 151876, 148, 14324, 125, 13468, 1306, 1144, 12345679, 12, 1158, 1036, 1, 1084, 962, 102428, 1, 98765432
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OFFSET
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1,1
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LINKS
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FORMULA
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MATHEMATICA
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f[n_] := Block[{id = {0, 4}, k = 1}, While[ Union[ Join[id, IntegerDigits[k*n]]] != id, k++]; k]; Array[f, 100] (* or *)
id = {0, 7}; lst = Union[ FromDigits /@ Flatten[ Table[ Tuples[id, j], {j, 15}], 1]]; If[ lst[[1]] == 0, lst = Rest@ lst]; f[n_] := (Min[ Select[lst, Mod[#, n] == 0 &]]/n) /. Infinity -> 0; Array[f, 100] (* or *)
id = {0, 7}; lst = Union[ FromDigits /@ Flatten[ Table[ Tuples[id, j], {j, 15}], 1]]; If[ lst[[1]] == 0, lst = Rest@ lst]; f[n_] := (SelectFirst[lst, Mod[#, n] == 0 &, 0]/n); a = Array[f, 100] (* requires Mathematica v10 *) (* Robert G. Wilson v, Sep 26 2016 *)
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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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STATUS
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approved
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