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A022566
Numbers that are not the sum of 4 nonnegative cubes.
10
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
Jean-Marc Deshouillers, Francois Hennecart and Bernard Landreau; appendix by I. Gusti Putu Purnaba, 7373170279850, Math. Comp., Vol. 69, No. 229 (2000), 421-439.
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
KEYWORD
nonn,easy,fini,nice
EXTENSIONS
More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001
STATUS
approved