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A134608
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Composite numbers such that the cube root of the sum of cubes of their prime factors is an integer.
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20
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256, 588, 693, 3840, 6561, 14157, 17787, 141960, 178360, 313600, 337365, 350000, 387072, 390625, 407442, 432000, 466560, 531674, 535815, 541310, 664909, 697851, 1044582, 1262056, 1264640, 1299272, 1374327, 1547570, 1608575, 1660360
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refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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LINKS
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Hieronymus Fischer, Table of n, a(n) for n = 1..300
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EXAMPLE
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a(3)=693, since 693=3*3*7*11 and (2*3^3+7^3+11^3)^(1/3)=1728^(1/3)=12.
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MATHEMATICA
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criQ[n_]:=IntegerQ[Surd[Total[Flatten[Table[#[[1]], #[[2]]]&/@ FactorInteger[ n]]^3], 3]]; Select[Range[1670000], CompositeQ[#] && criQ[#]&] (* Harvey P. Dale, Sep 19 2021 *)
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PROG
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(PARI) lista(m) = {for (i=2, m, if (! isprime(i), f = factor(i); s = sum (j=1, length(f~), f[j, 1]^3*f[j, 2]); if (ispower(s, 3), print1(i, ", ")); ); ); } \\ Michel Marcus, Apr 14 2013
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CROSSREFS
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Cf. A001597, A025475, A134333, A134344, A134376.
Cf. A134600, A134602, A134605, A134611, A134616, A134618, A134620.
Sequence in context: A206137 A206130 A110297 * A134609 A260065 A329488
Adjacent sequences: A134605 A134606 A134607 * A134609 A134610 A134611
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KEYWORD
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nonn
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AUTHOR
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Hieronymus Fischer, Nov 11 2007
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EXTENSIONS
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Minor edits by Hieronymus Fischer, Apr 20 2013
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STATUS
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approved
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