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A275672 Size of a largest subset of a regular cubic lattice of n*n*n points without repeated distances. 0
0, 1, 3, 4, 6, 7, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

10 <= a(7) <= 12, 11 <= a(8) <= 13, 12 <= a(9) <= 15, 13 <= a(10) <= 17.

LINKS

Table of n, a(n) for n=0..6.

Math.StackExchange, A largest subset of a cubic lattice with unique distances between its points, Aug 03 2016.

Ed Pegg Jr, No Repeated Distances, Wolfram Demonstrations Project, May 03 2013.

A. Zimmermann. Al Zimmermann's Programming Contests: Point Packing, Oct 10 2009.

EXAMPLE

For n = 5, a(5) >= 7 is witnessed by {(1,1,1), (1,1,2), (1,1,4), (1,2,5), (2,3,1), (4,4,5), (5,5,4)}. There are 4223 distinct (up to rotation and reflection) 7-point configurations without repeated distances, and none of them can be extended to 8 points, so a(5) = 7.

CROSSREFS

Cf. A003022, A054578, A036501, A169942.

Sequence in context: A322376 A044813 A154661 * A087753 A233334 A320300

Adjacent sequences:  A275669 A275670 A275671 * A275673 A275674 A275675

KEYWORD

nonn,hard,more

AUTHOR

Vladimir Reshetnikov, Aug 04 2016

STATUS

approved

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Last modified October 16 02:52 EDT 2019. Contains 328038 sequences. (Running on oeis4.)