A057962 - OEIS

A057962

Number of points (x,y) in square lattice with (x-1/2)^2+(y-1/2)^2 <= n.

4, 12, 16, 24, 32, 44, 52, 60, 68, 76, 80, 88, 96, 112, 120, 124, 140, 148, 156, 164, 172, 180, 188, 192, 208, 216, 232, 240, 248, 256, 268, 276, 284, 300, 308, 316, 332, 348, 360, 368, 376, 384, 392, 400, 408, 424, 432, 440, 448, 460, 468, 484, 492, 500

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

OFFSET

1,1

COMMENTS

Always a multiple of 4. Useful for rasterizing circles.

REFERENCES

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 106.

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

a(2)=12 because (-1,0); (-1,1); (0,-1); (0,0); (0,1); (0,2); (1,-1); (1,0); (1,1); (1,2); (2,0); (2,1) are covered by any disc of radius between sqrt(2.5) and sqrt(4.5) and centered at (0.5,0.5).

CROSSREFS

Cf. A057961, A004018, A004020. Partial sums of A005883.

Sequence in context: A053006 A328849 A261958 * A186303 A073687 A187084

Adjacent sequences: A057959 A057960 A057961 * A057963 A057964 A057965

KEYWORD

easy,nonn

AUTHOR

Ken Takusagawa, Oct 15 2000

STATUS

approved