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A008917
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Numbers that are the sum of 3 positive cubes in more than one way.
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13
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251, 1009, 1366, 1457, 1459, 1520, 1730, 1737, 1756, 1763, 1793, 1854, 1945, 2008, 2072, 2241, 2414, 2456, 2458, 2729, 2736, 3060, 3391, 3457, 3592, 3599, 3655, 3745, 3926, 4105, 4112, 4131, 4168, 4229, 4320, 4376, 4402, 4437, 4447
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OFFSET
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1,1
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COMMENTS
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Of course reordering the terms does not count.
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LINKS
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Christian N. K. Anderson, Decomposition of first 10000 terms into multiple cube triples.
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EXAMPLE
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a(2) = 1009 = 1^3+2^3+10^3 = 4^3+6^3+9^3.
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MATHEMATICA
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Select[Range[4450], 1 < Length @ Cases[PowersRepresentations[#, 3, 3], {_?Positive, _?Positive, _?Positive}] &] (* Jean-François Alcover, Apr 04 2011 *)
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PROG
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(PARI) is(n)=k=ceil((n-2)^(1/3)); d=0; for(a=1, k, for(b=a, k, for(c=b, k, if(a^3+b^3+c^3==n, d++)))); d
n=3; while(n<5000, if(is(n)>1, print1(n, ", ")); n++) \\ Derek Orr, Aug 27 2015
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CROSSREFS
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KEYWORD
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nonn,easy,nice
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AUTHOR
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STATUS
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approved
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