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A025228
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a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 3.
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7
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2, 1, 4, 17, 76, 354, 1704, 8421, 42508, 218318, 1137400, 5996938, 31940792, 171605956, 928931280, 5061593709, 27739833228, 152809506582, 845646470616, 4699126915422, 26209721959656, 146681521121244, 823429928805936, 4635568494271458
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OFFSET
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1,1
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COMMENTS
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Essentially A005572 shifted right twice, and 2 prepended.
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LINKS
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FORMULA
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MATHEMATICA
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Rest[CoefficientList[Series[(1-Sqrt[1-8x+12x^2])/2, {x, 0, 30}], x]] (* Harvey P. Dale, Apr 20 2011 *)
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PROG
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(PARI) a(n)=polcoeff((1-sqrt(1-8*x+12*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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