A036558 Squared distances that can arise in any Barlow packing of spheres of diameter sqrt(3) (the scale being the simplest one that makes this an integer sequence).

0, 3, 6, 8, 9, 11, 12, 15, 17, 18, 19, 20, 21, 22, 24, 25, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 41, 43, 44, 45, 46, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86

Offset

0,2

Links

Table of n, a(n) for n=0..67.

Formula

The set of all values of N = xx + xy + yy + 2zz for which x, y, z are integers subject to the proviso that N must be a multiple of 3 if |z| < 2.

Crossrefs

Complement of A036559.

Sequence in context: A004715 A280272 A190234 * A005870 A194461 A186385

Adjacent sequences: A036555 A036556 A036557 * A036559 A036560 A036561

Keyword

nonn

Author

J. H. Conway, N. J. A. Sloane.

Status

approved