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A377568
Numbers k with the property that the maximum density of points in the integer lattice with all distances at least sqrt(k) is 1/k.
0
1, 2, 4, 5, 8, 9, 10, 16, 18, 20, 32, 36, 49, 81
OFFSET
1,2
COMMENTS
All of these are sums of two squares.
These distances can be achieved by points on a tilted square lattice.
EXAMPLE
The smallest density of lattice points with distances at least sqrt(5) has density 1/5, so 5 is in the sequence:
o....o.
..o....
....o..
.o....o
...o...
o....o.
But the smallest density of lattice points with distances at least sqrt(13) has density 1/12, so 13 is not in the sequence:
o.....o
.......
...o...
.......
o.....o
.......
...o...
CROSSREFS
Subsequence of A001481.
Sequence in context: A010443 A035269 A267703 * A277075 A038558 A286031
KEYWORD
nonn,fini,full
AUTHOR
Erich Friedman, Nov 04 2024
STATUS
approved