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

Author

N. J. A. Sloane

Keywords

• nonn
• easy
• fini
• nice

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

Crossrefs

Cf. A025448.

Programs

Mathematica

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

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

Extensions

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