A028964 Numbers represented by quadratic form with Gram matrix [ 2, 1, 1; 1, 4, 2; 1, 2, 4 ], divided by 2.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 36, 37, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77

Offset

1,3

Links

Table of n, a(n) for n=1..72.

Maple

L := [seq(0, i=1..1)]: for x from -20 to 20 do for y from -20 to 20 do for z from -20 to 20 do if member(2*x^2+2*x*y+2*x*z+4*y^2+4*y*z+4*z^2, L)=false then L := [op(L), 2*x^2 +2*x*y+2*x*z+4*y^2+4*y*z+4*z^2] fi: od: od: od: L2 := sort(L): for i from 1 to 100 do printf(`%d, `, L2[i]/2) od:

Crossrefs

Sequence in context: A253643 A050743 A306311 * A219361 A191878 A122154

Adjacent sequences: A028961 A028962 A028963 * A028965 A028966 A028967

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from James A. Sellers, May 31 2000

Status

approved