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A009117
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Expansion of e.g.f.: 1/2 + exp(-4*x)/2.
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6
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1, -2, 8, -32, 128, -512, 2048, -8192, 32768, -131072, 524288, -2097152, 8388608, -33554432, 134217728, -536870912, 2147483648, -8589934592, 34359738368, -137438953472, 549755813888, -2199023255552, 8796093022208, -35184372088832, 140737488355328, -562949953421312
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OFFSET
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0,2
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LINKS
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FORMULA
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1 followed by (-4)^n /2.
E.g.f.: cos(x)^2 (even powers).
E.g.f.: 1/2 + exp(-4*x)/2 = (G(0)+1)/2 ; G(k) = 1 - 4*x/(2*k+1 - 2*x*(2*k+1)/(2*x - (k+1)/G(k+1))) ; (continued fraction). - Sergei N. Gladkovskii, Dec 20 2011
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MAPLE
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MATHEMATICA
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With[{nn=30}, CoefficientList[Series[1/2+Exp[-4x]/2, {x, 0, nn}], x] Range[ 0, nn]!] (* or *) LinearRecurrence[{-4}, {1, -2}, 30] (* Harvey P. Dale, Apr 09 2015 *)
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PROG
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(PARI) x='x+O('x^100); Vec((1+2*x)/(1+4*x)) \\ Altug Alkan, Dec 21 2015
(Magma) m:=30; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((2*x+1)/(1+4*x))); // G. C. Greubel, Jul 26 2018
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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