A330708 Numbers that are not the sum of 2 nonzero squares and a positive cube.

0, 1, 2, 4, 5, 7, 8, 12, 15, 17, 20, 22, 23, 24, 31, 36, 39, 43, 50, 55, 57, 63, 65, 70, 71, 78, 87, 94, 103, 111, 113, 115, 119, 120, 134, 139, 141, 148, 160, 167, 169, 185, 204, 211, 254, 263, 267, 279, 283, 286, 302, 311, 312, 331, 335, 342, 349, 379, 391

Offset: 1

Author

XU Pingya, Jun 08 2020

Keywords

• nonn

Comments

A022552 is a subsequence.

a(490) = A022552(434) = 5042631. No more terms <= 4 * 10^7.

Links

• Robert Israel, Table of n, a(n) for n = 1..490

Crossrefs

Cf. A022552, A000534, A004214.

Programs

Maple

N:= 500: # for terms <= N
G1:= add(x^(i^2), i=1..floor(sqrt(N))):
G2:= add(x^(i^3), i=1..floor(N^(1/3))):
G:= expand(G1^2*G2):
select(t -> coeff(G,x,t)=0, [$0..N]); # Robert Israel, Jun 12 2020

Mathematica

m = 0;
n = 400.;
t = Union@Flatten@Table[x^2 + y^2 + z^3, {x, (n/2)^(1/2)}, {y, x, (n - x^2)^(1/2)}, {z, If[x^2 + y^2 < m, Floor[(m - 1 - x^2 - y^2)^(1/3)] + 1, 1], (n - x^2 - y^2)^(1/3)}];
Complement[Range[m, n], t]