A135607 Floor of the area of a circle in terms of its circumference n.

0, 0, 0, 0, 1, 1, 2, 3, 5, 6, 7, 9, 11, 13, 15, 17, 20, 22, 25, 28, 31, 35, 38, 42, 45, 49, 53, 58, 62, 66, 71, 76, 81, 86, 91, 97, 103, 108, 114, 121, 127, 133, 140, 147, 154, 161, 168, 175, 183, 191, 198, 206, 215, 223, 232, 240, 249, 258, 267, 277, 286, 296, 305, 315

Offset: 0

Author

Cino Hilliard, Feb 27 2008

Keywords

• nonn

Examples

			For a circle of circumference 10, the floor of the area A = floor(100/4/Pi) = 7.
		

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A038130, A066643, A135039.

Programs

Mathematica

Table[Floor[n^2/(4*Pi)], {n,0,25}] (* G. C. Greubel, Oct 21 2016 *)

PARI

g(n) = for(c=0,n,a=c^2/4/Pi;print1(floor(a)","))

PARI

a(n) = n^2\(4*Pi); \\ Michel Marcus, Oct 22 2016

Formula

Area of a circle of radius r is A = Pi*r^2. Circumference of a circle of radius r is n = 2*Pi*r. Then area in terms of the circumference n is A = n^2/(4*Pi).