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A066797
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a(n) = Sum_{i=1..n} binomial(4*i,2*i).
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2
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6, 76, 1000, 13870, 198626, 2902782, 43019382, 644099772, 9719235072, 147565763892, 2251664727612, 34499268410712, 530417801358816, 8179108402119256, 126443689966980680, 1959067830909571214
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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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G.f.: ((1+4*sqrt(x))^(-1/2) + (1-4*sqrt(x))^(-1/2) - 2)/(2-2*x). - Mark van Hoeij, May 02 2013
Recurrence: n*(2*n-1)*a(n) = (34*n^2 - 33*n + 6)*a(n-1) - 2*(4*n-3)*(4*n-1)*a(n-2). - Vaclav Kotesovec, Aug 16 2013
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PROG
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(PARI) { a=0; for (n=1, 150, write("b066797.txt", n, " ", a+=binomial(4*n, 2*n)) ) } \\ Harry J. Smith, Mar 27 2010
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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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