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A113505
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Numbers not the sum of at most three perfect powers (A001597).
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6
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7, 15, 23, 87, 111, 119, 167, 335, 1391, 1455, 1607, 1679, 1991, 25887, 26375
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Cannot be written in the form a^x + b^y + c^z with a, b, c >= 0 and x, y, z > 1.
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LINKS
| Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
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MATHEMATICA
| lmt = 40000; s = Union@ Join[{0, 1}, Flatten@ Table[n^i, {n, 2, Sqrt@ lmt}, {i, 2, Log[n, lmt]}]]; t = Select[ Union[Plus @@@ Tuples[s, 3]], # < lmt + 1 &]; Complement[Range@ lmt, t] (* Robert G. Wilson v *)
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CROSSREFS
| A056828 is a subset, A001694.
Sequence in context: A194400 A177768 A056828 * A184920 A076796 A056119
Adjacent sequences: A113502 A113503 A113504 * A113506 A113507 A113508
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KEYWORD
| nonn
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AUTHOR
| R. P. van der Hilst (R.P.vanderHilst(AT)students.uu.nl), Jan 12 2006
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(at)rgwv.com), May 01 2006
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