A022566 Numbers that are not the sum of 4 nonnegative cubes.

5, 6, 7, 12, 13, 14, 15, 19, 20, 21, 22, 23, 26, 31, 33, 34, 38, 39, 40, 41, 42, 45, 46, 47, 48, 49, 50, 52, 53, 57, 58, 59, 60, 61, 68, 69, 71, 75, 76, 77, 78, 79, 83, 84, 85, 86, 87, 90, 94, 95, 96, 97, 98, 101, 102, 103, 104, 105, 106, 109, 110, 111, 112, 113, 114, 115

Offset

1,1

Comments

From Felix Fröhlich, Jun 01 2019: (Start)

Numbers n such that A025448(n) = 0.

Conjecture: The sequence is finite, with 113936676 terms, the largest being 7373170279850 (cf. Deshouillers et al, 2000, Conj. 1 and 2). (End)

Links

T. D. Noe, Table of n, a(n) for n = 1..10000

Jean-Marc Deshouillers, Francois Hennecart and Bernard Landreau; appendix by I. Gusti Putu Purnaba, 7373170279850, Math. Comp., Vol. 69, No. 229 (2000), 421-439.

Index entries for sequences related to sums of cubes

Mathematica

Complement[Range[134], Take[Union[Total[#^3]&/@Tuples[Range[0, 20], {4}]], 60]] (* Harvey P. Dale, Nov 22 2010 *)

Prog

(PARI) cubes(bound) = my(v=[], x=0); while(1, v=concat(v, [x^3]); x++; if(x^3 > bound, return(v)))
a025448(n) = my(i=0, c=cubes(n)); for(s=1, #c, for(t=s, #c, for(u=t, #c, for(v=u, #c, if(n==c[s]+c[t]+c[u]+c[v], i++))))); i
is(n) = a025448(n)==0 \\ Felix Fröhlich, Jun 01 2019

Crossrefs

Cf. A025448.

Sequence in context: A154952 A037360 A120521 * A047320 A327301 A247522

Adjacent sequences: A022563 A022564 A022565 * A022567 A022568 A022569

Keyword

nonn,easy,fini,nice

Author

N. J. A. Sloane

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001

Status

approved