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A004999
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Sums of two nonnegative cubes.
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9
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0, 1, 2, 8, 9, 16, 27, 28, 35, 54, 64, 65, 72, 91, 125, 126, 128, 133, 152, 189, 216, 217, 224, 243, 250, 280, 341, 343, 344, 351, 370, 407, 432, 468, 512, 513, 520, 539, 559, 576, 637, 686, 728, 729, 730, 737, 756, 793, 854, 855, 945, 1000, 1001
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refs;
listen;
history;
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OFFSET
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1,3
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..1000
Kevin A. Broughan, Characterizing the Sum of Two Cubes, J. Integer Seqs., Vol. 6, 2003.
Index entries for sequences related to sums of cubes
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MATHEMATICA
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Union[(#[[1]]^3+#[[2]]^3)&/@Tuples[Range[0, 20], {2}]]
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PROG
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(PARI) is(n)=my(k1=ceil((n-1/2)^(1/3)), k2=floor((4*n+1/2)^(1/3)), L); fordiv(n, d, if(d>=k1 && d<=k2 && denominator(L=(d^2-n/d)/3)==1 && issquare(d^2-4*L), return(1))); 0
list(lim)=my(v=List()); for(x=0, (lim+.5)^(1/3), for(y=0, min(x, (lim-x^3)^(1/3)), listput(v, x^3+y^3))); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, Jun 12 2012
(PARI) is(n)=my(L=sqrtnint(n-1, 3)+1, U=sqrtnint(4*n, 3)); fordiv(n, m, if(L<=m&m<=U, my(ell=(m^2-n/m)/3); if(denominator(ell)==1&&issquare(m^2-4*ell), return(1)))); 0 \\ Charles R Greathouse IV, Apr 16 2013
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CROSSREFS
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Sequence in context: A056805 A226825 A046679 * A105125 A220263 A033492
Adjacent sequences: A004996 A004997 A004998 * A005000 A005001 A005002
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KEYWORD
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nonn,easy,nice
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AUTHOR
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N. J. A. Sloane, Steven Finch
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EXTENSIONS
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Mathematica program provided by Harvey P. Dale, Dec 04 2010
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STATUS
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approved
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