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A278257
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Least number with the prime signature of A005187(n).
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1
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1, 2, 4, 2, 8, 6, 2, 6, 16, 12, 2, 6, 2, 4, 6, 2, 32, 6, 6, 6, 6, 2, 30, 6, 2, 4, 12, 2, 24, 24, 6, 12, 64, 30, 2, 30, 2, 2, 6, 30, 2, 16, 6, 6, 6, 24, 2, 6, 6, 2, 12, 2, 30, 24, 30, 2, 30, 48, 2, 12, 12, 6, 120, 2, 128, 30, 2, 6, 24, 2, 30, 6, 6, 6, 6, 2, 60, 24, 12, 6, 6, 6, 48, 30, 6, 120, 4, 2, 30, 48, 6, 180, 2, 6, 24, 30, 2, 2, 6, 2, 60, 72, 6, 6, 6, 48
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OFFSET
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1,2
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LINKS
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FORMULA
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MATHEMATICA
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f[n_] := If[Length@ # == 1 && #[[1, 1]] == 1, {0}, Sort@ #[[All, -1]]] &@ FactorInteger@ n; Table[k = 1; While[f@ k != #, k++] &@ f[2 n - DigitCount[2 n, 2, 1]]; k, {n, 106}] (* or, faster *)
Table[Times @@ MapIndexed[(Prime@ First@ #2)^#1 &, #] &@ If[Length# == 1 && #[[1, 1]] == 1, {0}, Reverse@ Sort@ #[[All, -1]]] &@ FactorInteger[2 n - DigitCount[2 n, 2, 1]], {n, 106}] (* Michael De Vlieger, Nov 21 2016 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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