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A024491
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a(n) = (1/(4n-1))*C(4n,2n).
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1
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-1, 2, 10, 84, 858, 9724, 117572, 1485800, 19389690, 259289580, 3534526380, 48932534040, 686119227300, 9723892802904, 139067101832008, 2004484433302736
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| G.f.: A(x) = -sqrt(1/2*(1+sqrt(1-16*x)))
With interpolated zeros, this has g.f. -(sqrt(1-4x)+sqrt(1+4x))/2. - Paul Barry (pbarry(AT)wit.ie), Dec 23 2006
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EXAMPLE
| sqrt(1/2*(1+sqrt(1-x))) = 1 - 1/8*x - 5/128*x^2 - 21/1024*x^3 - ...
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CROSSREFS
| Cf. A024492.
Sequence in context: A101878 A121194 A121516 * A147316 A113332 A180715
Adjacent sequences: A024488 A024489 A024490 * A024492 A024493 A024494
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KEYWORD
| sign
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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