|
| |
|
|
A144873
|
|
If n mod 8 = 0 or n mod 10 = 0 then floor(n^2/4)+n otherwise floor(n^2/4)+n-1.
|
|
0
| |
|
|
0, 0, 2, 4, 7, 10, 14, 18, 24, 28, 35, 40, 47, 54, 62, 70, 80, 88, 98, 108, 120, 130, 142, 154, 168, 180, 194, 208, 223, 238, 255, 270, 288, 304, 322, 340, 359, 378, 398, 418, 440, 460, 482, 504, 527, 550, 574, 598, 624, 648, 675, 700, 727, 754, 782, 810, 840, 868, 898, 928
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
COMMENTS
| For n >= 5, this is the maximal number of pairs of points at unit distance in a set of n points in R^4.
|
|
|
REFERENCES
| K. J. Swanepoel, Unit distances and diameters in Euclidean spaces, Discrete Comput. Geom., 41 (No. 1, 2009), 1-27.
|
|
|
FORMULA
| a(n)=2*a(n-1)-a(n-2)+a(n-40)-2*a(n-41)+a(n-42). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Feb 13 2009]
|
|
|
MAPLE
| f:=proc(n) if n mod 8 = 0 or n mod 10 = 0 then floor(n^2/4)+n else floor(n^2/4)+n-1; fi; end;
|
|
|
CROSSREFS
| Sequence in context: A014616 A184674 A183136 * A120679 A145106 A127723
Adjacent sequences: A144870 A144871 A144872 * A144874 A144875 A144876
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Feb 13 2009
|
| |
|
|
