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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). 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 12 07:43 EDT 2021. Contains 344943 sequences. (Running on oeis4.)