A004999
Sums of two nonnegative cubes.
DATA
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, 1001PYTHON IMPLEMENTATION
No Python implementation recorded in the local database yet.
PROGRAMS
Mathematica
Union[(#[[1]]^3+#[[2]]^3)&/@Tuples[Range[0,20],{2}]] (* _Harvey P. Dale_, Dec 04 2010 *)
Other Programs
- (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
- (PARI) :
T=thueinit('z^3+1);
is(n)=n==0 || #select(v->min(v[1],v[2])>=0, thue(T,n))>0 \\ _Charles R Greathouse IV_, Nov 29 2014
- (Haskell) :
a004999 n = a004999_list !! (n-1) a004999_list = filter c2 [1..] where c2 x = any (== 1) $ map (a010057 . fromInteger) $ takeWhile (>= 0) $ map (x -) $ tail a000578_list -- _Reinhard Zumkeller_, Dec 20 2013
LINKS
- 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.
- Samuel S. Wagstaff, Jr., Equal Sums of Two Distinct Like Powers, J. Int. Seq., Vol. 25 (2022), Article 22.3.1.
- Index entries for sequences related to sums of cubes
CROSSREFERENCES
- Subsequence of A045980; A003325 is a subsequence.
- Cf. A000578, A004825, A010057, A373972 (characteristic function).
- Indices of nonzero terms in A025446.
- See also the official entry at https://oeis.org/A004999
METADATA
- OFFSET :
1,3 - KEYWORDS :
nonn,easy,nice - AUTHOR : N. J. A. Sloane, Steven Finch
- IDENTIFICATION :
#41 Jul 02 2024 07:23:35