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A163747
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E.g.f. 2*exp(x)*(1-exp(x))/(1+exp(2*x)).
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2
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0, -1, -1, 2, 5, -16, -61, 272, 1385, -7936, -50521, 353792, 2702765, -22368256, -199360981, 1903757312, 19391512145, -209865342976, -2404879675441, 29088885112832, 370371188237525, -4951498053124096, -69348874393137901
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,4
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COMMENTS
| The real part of the exponential expansion of 2*((1+i)/(1+i*exp(z))-1) = (-1-i)*z + (-1/2+i/2)*z^2+(1/3+i/3)*z^3+(5/24-5i/24)*z^4 + (-2/15-2i/15)*z^5+... where i is the imaginary unit.
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MAPLE
| A163747 := proc(n) exp(t)*(1-exp(t))/(1+exp(2*t)) ; coeftayl(%, t=0, n) ; 2*%*n! ; end proc: # R. J. Mathar, Sep 11 2011
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MATHEMATICA
| f[t_] = (1 + I)/(1 + I*Exp[t]) - 1 Table[Re[2*n!*SeriesCoefficient[ Series[f[t], {t, 0, 30}], n]], {n, 0, 30}]
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CROSSREFS
| Sequence in context: A178123 A138265 A000111 * A007976 A058259 A033543
Adjacent sequences: A163744 A163745 A163746 * A163748 A163749 A163750
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KEYWORD
| sign
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AUTHOR
| Roger L, Bagula (rlbagulatftn(AT)yahoo.com), Aug 03 2009
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