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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
OFFSET
0,3
COMMENTS
10 <= a(7) <= 12, 11 <= a(8) <= 13, 12 <= a(9) <= 15, 13 <= a(10) <= 17.
LINKS
Ed Pegg Jr, No Repeated Distances, Wolfram Demonstrations Project, May 03 2013.
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
KEYWORD
nonn,hard,more
AUTHOR
STATUS
approved