A297931 Numbers that are not the sum of a square and 3 nonnegative cubes.

15, 22, 23, 48, 86, 94, 112, 120, 139, 184, 203, 211, 230, 237, 263, 301, 309, 312, 335, 373, 399, 1014, 1056, 1455, 1644, 2029, 2272, 2658, 3309, 3469, 4019, 6502, 11101

Offset: 1

Author

XU Pingya, Jan 08 2018

Keywords

• nonn

Comments

After 11101, there are no more terms up to 570000.

No more terms < 10^10; is this sequence finite? - Mauro Fiorentini, Jan 26 2019

Links

• Eric Weisstein's World of Mathematics, Waring's Problem

Crossrefs

Cf. A004215, A022552, A022557, A022561, A022566, A111151.

Programs

Mathematica

t1={};
Do[Do[If[x^2+y^2+z^2+w^3==n, AppendTo[t1,n]&&Break[]], {x,0,n^(1/2)}, {y,x,(n-x^2)^(1/2)}, {z,y,(n-x^2-y^2)^(1/2)}, {w,0,(n-x^2-y^2-z^2)^(1/3)}], {n,0,5.7*10^5}];
t2={};
Do[If[FreeQ[t1,k]==True, AppendTo[t2,k]], {k,0,5.7*10^5}];
t2