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A120701 Number of unit circles which fit touching a circle of radius n-1, i.e., with their centers on a circle of radius n. 1
2, 6, 9, 12, 15, 18, 21, 25, 28, 31, 34, 37, 40, 43, 47, 50, 53, 56, 59, 62, 65, 69, 72, 75, 78, 81, 84, 87, 91, 94, 97, 100, 103, 106, 109, 113, 116, 119, 122, 125, 128, 131, 135, 138, 141, 144, 147, 150, 153, 157, 160, 163, 166, 169, 172, 175, 179, 182, 185, 188 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Coincides with A022844 = floor(n*Pi) except at n=1, 25510582, ... (sequence A120702).

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a(n) = floor(Pi/arcsin(1/n)).

MATHEMATICA

Table[Floor[Pi/ArcSin[1/n]], {n, 60}] (* Indranil Ghosh, Jul 21 2017 *)

PROG

(Python)

from mpmath import *

mp.dps=100

def a(n): return int(floor(pi/asin(1./n)))

print map(a, xrange(1, 61)) # Indranil Ghosh, Jul 21 2017

CROSSREFS

Cf. A001116, A002486, A022844.

Sequence in context: A119720 A173978 A000134 * A189752 A206813 A189371

Adjacent sequences:  A120698 A120699 A120700 * A120702 A120703 A120704

KEYWORD

easy,nonn

AUTHOR

Martin Fuller, Jun 28 2006

STATUS

approved

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Last modified September 17 17:32 EDT 2019. Contains 327136 sequences. (Running on oeis4.)