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A129369
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Expansion of 1/sqrt(1-4x)-x/sqrt(1-4x^2).
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4
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1, 1, 6, 18, 70, 246, 924, 3412, 12870, 48550, 184756, 705180, 2704156, 10399676, 40116600, 155114088, 601080390, 2333593350, 9075135300, 35345215180, 137846528820, 538257689684, 2104098963720, 8233430022168, 32247603683100
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Partial sums are A129368.
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FORMULA
| a(n)=C(2n,n)-C(n-1,(n-1)/2)(1-(-1)^n)/2;
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MATHEMATICA
| CoefficientList[Series[1/Sqrt[1-4x]-x/Sqrt[1-4x^2], {x, 0, 30}], x] (* From Harvey P. Dale, Feb 02 2012 *)
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CROSSREFS
| Sequence in context: A034751 A200151 A000623 * A095853 A027266 A027261
Adjacent sequences: A129366 A129367 A129368 * A129370 A129371 A129372
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 11 2007
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