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A008917 Numbers that are the sum of 3 positive cubes in more than one way. 7
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Of course reordering the terms does not count.

A025456(a(n)) > 1. [Reinhard Zumkeller, Apr 23 2009]

LINKS

T. D. Noe and Christian N. K. Anderson, Table of n, a(n) for n = 1..10000 (first 1000 terms are from T. D. Noe)

Christian N. K. Anderson, Decomposition of first 10,000 terms into multiple cube triplets.

EXAMPLE

a(2) = 1009 = 1^3+2^3+10^3 = 4^3+6^3+9^3.

MATHEMATICA

Select[Range[4450], 1 < Length @ Cases[PowersRepresentations[#, 3, 3], {_?Positive, _?Positive, _?Positive}] &]  (* Jean-Fran├žois Alcover, Apr 04 2011 *)

PROG

(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

CROSSREFS

Sequence in context: A179231 A108833 A228672 * A025396 A185941 A215607

Adjacent sequences:  A008914 A008915 A008916 * A008918 A008919 A008920

KEYWORD

nonn,easy,nice

AUTHOR

N. J. A. Sloane and J. H. Conway

STATUS

approved

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Last modified March 29 03:29 EDT 2017. Contains 284250 sequences.