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A046981
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Denominators of Taylor series for exp(x)*cos(x).
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6
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1, 1, 1, 3, 6, 30, 1, 630, 2520, 22680, 1, 1247400, 7484400, 97297200, 1, 10216206000, 81729648000, 1389404016000, 1, 237588086736000, 2375880867360000, 49893498214560000, 1, 12623055048283680000, 151476660579404160000, 3786916514485104000000
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OFFSET
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0,4
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REFERENCES
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G. W. Caunt, Infinitesimal Calculus, Oxford Univ. Press, 1914, p. 477.
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LINKS
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FORMULA
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a(4n+2) = 1, a(n) = n!/2^[n/2].
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EXAMPLE
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1+1*x-1/3*x^3-1/6*x^4-1/30*x^5+1/630*x^7+1/2520*x^8+1/22680*x^9-...
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MATHEMATICA
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Denominator/@CoefficientList[Series[Exp[x]Cos[x], {x, 0, 30}], x] (* Harvey P. Dale, Jun 28 2011 *)
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CROSSREFS
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Absolute values are essentially the same as A007452.
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KEYWORD
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nonn,frac,easy,nice
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AUTHOR
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STATUS
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approved
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