A008917 Numbers that are the sum of 3 positive cubes in more than one way.

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

Offset: 1

Author

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

Keywords

• nonn
• easy
• nice

Comments

Of course reordering the terms does not count.

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

Examples

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

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 10000 terms into multiple cube triples.

Crossrefs

Cf. A001235, A003072, A024796, A025396, A025398, A025406, A309762.

Programs

Mathematica

Select[Range[4450], 1 < Length @ Cases[PowersRepresentations[#, 3, 3], {?Positive, ?Positive, ?Positive}] &]  (* _Jean-François Alcover, Apr 04 2011 *)

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