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Search: id:A090081
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| A090081 |
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Nonprimes n such that largest prime factor of n does not exceed cube root of n. |
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1
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| 1, 8, 16, 27, 32, 36, 48, 54, 64, 72, 81, 96, 108, 125, 128, 135, 144, 150, 160, 162, 180, 192, 200, 216, 225, 240, 243, 250, 256, 270, 288, 300, 320, 324, 343, 350, 360, 375, 378, 384, 392, 400, 405, 420, 432, 441, 448, 450, 480, 486, 490, 500, 504, 512, 525
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Nonprime solutions to A006530[n]<=n^(1/3).
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EXAMPLE
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n=378=2.3.3.3.7, n^(1/3)~7.23>7=A006530[378].
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MATHEMATICA
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ffi[x_] := Flatten[FactorInteger[x]]; ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}]; lf[x_] := Length[FactorInteger[x]]; ma[x_] := Max[ba[x]]; Do[If[ !Greater[ma[n], gy=n^(1/3)//N]&&!PrimeQ[n], Print[n(*, {gy, ma[n]}}*)]], {n, 1, 1000}]
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CROSSREFS
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Cf. A063763, A001248, A048098, A036966, A054744, A059172, A068936, A076405, A076467.
Sequence in context: A125991 A028589 A074750 this_sequence A059172 A107606 A036966
Adjacent sequences: A090078 A090079 A090080 this_sequence A090082 A090083 A090084
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Nov 21 2003
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