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A119661
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a(n) = floor(Pi/arccos(n/(n+1))).
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1
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3, 3, 4, 4, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19
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OFFSET
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1,1
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COMMENTS
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Let N(m1, m2, m3) be the maximum possible number of pairwise elastic collisions in a dynamic system of 3 point masses m1, m2, m3 on a line. N(m1,m2, m3) is independent of initial velocities and coordinates of masses m1, m2, m3. If m1 = n*m2 = m3 then N(m1, m2, m3) = -[-Pi/arccos(sqrt(m1*m3/((m1+m2)*(m2+m3))))] = a(n).
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LINKS
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G. A. Galperin, A. N. Zemliakov, Mathematical Billiards, "KVANT" Library, Issue 77, Moscow, Nauka, 1990, p. 165. (in Russian)
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EXAMPLE
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n = 24, -Pi/arccos(n/(n+1)) = -11.06997134, [-11.06997134] = -11. Therefore a(24) = 11.
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MAPLE
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seq(-trunc(-Pi/arccos(n/(n+1))), n=1..76); # Peter Luschny, Jun 28 2018
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MATHEMATICA
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Table[ -IntegerPart[ -Pi/ArcCos[ n/(n+1) ] ], {n, 1, 100}]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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