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A120701
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Number of unit circles which fit touching a circle of radius n-1, i.e., with their centers on a circle of radius n.
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1
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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
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refs;
listen;
history;
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internal format)
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OFFSET
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1,1
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COMMENTS
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Coincides with A022844 = floor(n*Pi) except at n=1, 25510582, ... (sequence A120702).
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LINKS
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Table of n, a(n) for n=1..60.
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FORMULA
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a(n) = floor(Pi/arcsin(1/n)).
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MATHEMATICA
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Table[Floor[Pi/ArcSin[1/n]], {n, 60}] (* Indranil Ghosh, Jul 21 2017 *)
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PROG
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(Python)
from mpmath import mp, pi, asin
mp.dps=100
def a(n): return int(floor(pi/asin(1./n)))
print([a(n) for n in range(1, 61)]) # Indranil Ghosh, Jul 21 2017
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CROSSREFS
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Cf. A001116, A002486, A022844, A120702.
Sequence in context: A119720 A173978 A000134 * A350235 A189752 A206813
Adjacent sequences: A120698 A120699 A120700 * A120702 A120703 A120704
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KEYWORD
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easy,nonn
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AUTHOR
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Martin Fuller, Jun 28 2006
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STATUS
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approved
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