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A025240
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a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-2)*a(2) for n >= 3.
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2
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3, 2, 6, 22, 90, 394, 1806, 8558, 41586, 206098, 1037718, 5293446, 27297738, 142078746, 745387038, 3937603038, 20927156706, 111818026018, 600318853926, 3236724317174, 17518619320890, 95149655201962, 518431875418926, 2832923350929742
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OFFSET
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1,1
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LINKS
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FORMULA
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Conjecture: n*a(n) +3*(-2*n+3)*a(n-1) +(n-3)*a(n-2)=0. - R. J. Mathar, Feb 25 2015
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MATHEMATICA
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Rest[CoefficientList[Series[(1+3x-Sqrt[1-6x+x^2])/2, {x, 0, 40}], x]] (* Harvey P. Dale, Aug 26 2013 *)
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PROG
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(PARI) a(n)=polcoeff((1+3*x-sqrt(1-6*x+x^2+x*O(x^n)))/2, n)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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