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A196361
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Decimal expansion of the absolute minimum of cos(t) + cos(2t) + cos(3t).
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8
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1, 3, 1, 5, 5, 6, 5, 1, 5, 4, 7, 2, 0, 4, 4, 9, 4, 1, 2, 3, 5, 2, 2, 7, 0, 7, 5, 0, 9, 4, 3, 5, 1, 1, 9, 6, 2, 2, 2, 1, 1, 7, 8, 3, 0, 6, 7, 2, 5, 0, 7, 9, 6, 7, 6, 3, 9, 1, 7, 9, 0, 4, 1, 5, 3, 4, 8, 4, 2, 5, 2, 5, 0, 4, 6, 7, 1, 1, 0, 5, 7, 0, 1, 6, 0, 1, 0, 1, 8, 5, 9, 4, 5, 6, 3, 6, 3, 1, 5
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OFFSET
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1,2
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COMMENTS
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The function f(x) = cos(x) + cos(2x) + ... + cos(nx), where n >= 2, attains an absolute minimum at some c between 0 and Pi. Related sequences (with graphs in Mathematica programs):
n x min(f(x))
= ======= =========
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LINKS
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FORMULA
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EXAMPLE
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x = 1.2929430585054266652256311954691354...
min(f(x)) = -1.3155651547204494123522707...
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MATHEMATICA
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n = 3; f[t_] := Cos[t]; s[t_] := Sum[f[k*t], {k, 1, n}];
x = N[Minimize[s[t], t], 110]; u = Part[x, 1]
v = 2 Pi - t /. Part[x, 2]
Plot[s[t], {t, -3 Pi, 3 Pi}]
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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