

A306469


Numbers not of the form x^2+2*y^2+2*y*z+4*z^2 (with x, y, z all >= 0).


2



7, 10, 14, 15, 21, 30, 35, 39, 42, 63, 70, 79, 84, 91, 94, 119, 126, 130, 133, 140, 168, 175, 182, 189, 210, 217, 231, 238, 259, 266, 280, 287, 315, 329, 336, 343, 359, 364, 378, 382, 385, 391, 399, 413, 427, 434, 462, 476, 483, 490, 511, 525, 532, 546, 560
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OFFSET

1,1


COMMENTS

It appears that the only terms not divisible by 7 are 10, 15, 30, 39, 79, 94, 130, 359, 382, 391, 754, and 1546.  Robert Israel, Mar 27 2019


LINKS



MAPLE

N:= 1000: # for terms <= N
V:= Array(0..N):
for x from 0 while x^2<=N do
for y from 0 while x^2 + 2*y^2 <= N do
for z from 0 do
v:= x^2 + 2*y^2 + 2*y*z + 4*z^2;
if v > N then break fi;
V[v]:= 1;
od od od:


CROSSREFS

Cf. A097634 (without the nonnegative requirement).


KEYWORD

nonn


AUTHOR



EXTENSIONS



STATUS

approved



