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A047085
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a(n) = T(2*n, n), array T as in A047080.
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10
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1, 1, 3, 9, 27, 83, 259, 817, 2599, 8323, 26797, 86659, 281287, 915907, 2990383, 9786369, 32092959, 105435607, 346950321, 1143342603, 3772698725, 12463525229, 41218894577, 136451431723, 452116980643, 1499282161375, 4975631425581, 16524213199923, 54913514061867
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: sqrt((1 - x)/(1 - 3*x - x^2 - x^3)). (End)
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MATHEMATICA
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CoefficientList[Series[Sqrt[(1-x)/(1-3*x-x^2-x^3)], {x, 0, 50}], x] (* G. C. Greubel, Oct 30 2022 *)
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PROG
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(Magma) R<x>:=PowerSeriesRing(Rationals(), 50); Coefficients(R!( Sqrt((1-x)/(1 -3*x-x^2-x^3)) )); // G. C. Greubel, Oct 30 2022
(SageMath)
P.<x> = PowerSeriesRing(ZZ, prec)
return P( sqrt((1-x)/(1-3*x-x^2-x^3)) ).list()
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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