A000398 Numbers of form x^2 + 2y^2 + 2yz + 4z^2.

0, 1, 2, 3, 4, 5, 6, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 40, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64

Offset

1,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

q=16; imax=q^2; Select[Union[Flatten[Table[x^2+2*y^2+2*y*z+4*z^2, {z, -q, q}, {y, 0, q}, {x, 0, q}]]], #<=imax&] (* Vladimir Joseph Stephan Orlovsky, Apr 19 2011 *)

Crossrefs

Complement of A097634.

Sequence in context: A303878 A039170 A097624 * A039267 A039206 A039118

Adjacent sequences: A000395 A000396 A000397 * A000399 A000400 A000401

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved