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A025232
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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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4
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3, 2, 12, 76, 504, 3472, 24672, 179792, 1337376, 10117312, 77618304, 602528640, 4724294400, 37361809920, 297683352576, 2387325283584, 19255919325696, 156110855965696, 1271401468151808
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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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a(n) ~ sqrt(3*sqrt(2)-2) * (2*(3+sqrt(2)))^n / (2*sqrt(14*Pi)*n^(3/2)). - Vaclav Kotesovec, Oct 11 2013
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MATHEMATICA
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Rest[CoefficientList[Series[(1-Sqrt[1-12*x+28*x^2])/2, {x, 0, 20}], x]] (* Vaclav Kotesovec, Oct 11 2013 *)
nxt[{n_, a_, b_, c_}]:={n+1, b, c, (c(12n-6)-28(n-2)*b)/(n+1)}; NestList[ nxt, {3, 3, 2, 12}, 20][[All, 2]] (* Harvey P. Dale, Jun 04 2019 *)
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PROG
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(PARI) a(n)=polcoeff((1-sqrt(1-12*x+28*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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