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 A134608 Composite numbers such that the cube root of the sum of cubes of their prime factors is an integer. 20
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Hieronymus Fischer, Table of n, a(n) for n = 1..300 EXAMPLE a(3)=693, since 693=3*3*7*11 and (2*3^3+7^3+11^3)^(1/3)=1728^(1/3)=12. MATHEMATICA criQ[n_]:=IntegerQ[Surd[Total[Flatten[Table[#[[1]], #[[2]]]&/@ FactorInteger[ n]]^3], 3]]; Select[Range[1670000], CompositeQ[#] && criQ[#]&] (* Harvey P. Dale, Sep 19 2021 *) PROG (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 CROSSREFS 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 KEYWORD nonn AUTHOR Hieronymus Fischer, Nov 11 2007 EXTENSIONS Minor edits by Hieronymus Fischer, Apr 20 2013 STATUS approved

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Last modified March 30 06:16 EDT 2023. Contains 361606 sequences. (Running on oeis4.)