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A330708
Numbers that are not the sum of 2 nonzero squares and a positive cube.
1
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
1,3
COMMENTS
A022552 is a subsequence.
a(490) = A022552(434) = 5042631. No more terms <= 4 * 10^7.
LINKS
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]
CROSSREFS
KEYWORD
nonn
AUTHOR
XU Pingya, Jun 08 2020
STATUS
approved