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A135607 Floor of the area of a circle in terms of its circumference n. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

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

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).

EXAMPLE

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

MATHEMATICA

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

PROG

(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

CROSSREFS

Cf. A038130, A066643, A135039.

Sequence in context: A057165 A245395 A023884 * A026453 A026455 A082984

Adjacent sequences:  A135604 A135605 A135606 * A135608 A135609 A135610

KEYWORD

nonn

AUTHOR

Cino Hilliard, Feb 27 2008

STATUS

approved

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Last modified November 13 19:25 EST 2018. Contains 317149 sequences. (Running on oeis4.)