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A084224
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Denominators of successive approximations to zeta(3) = Sum_{k>0} 1/k^3, using Zeilberger's formula with s=2.
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2
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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) = denominator( Sum_{k=1..n} (1/4)*(-1)^(k-1)*(56*k^2-32*k+5)/((2*k-1)^2 * binomial(3*k,k) * binomial(2*k,k) * k^3) ). - G. C. Greubel, Oct 08 2018
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MAPLE
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a:=n->add((1/4)*(-1)^(k-1)*(56*k^2-32*k+5)/((2*k-1)^2*binomial(3*k, k)*binomial(2*k, k)*k^3), k=1..n): seq(denom(a(n)), n=1..10); # Muniru A Asiru, Oct 09 2018
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MATHEMATICA
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Table[Denominator[Sum[(1/4)*(-1)^(k-1)*(56*k^2-32*k+5)/((2*k-1)^2*Binomial[3*k, k]* Binomial[2*k, k]*k^3), {k, 1, n}]], {n, 1, 30}] (* G. C. Greubel, Oct 08 2018 *)
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PROG
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(PARI) for(n=1, 15, print1(denominator(sum(k=1, n, (1/4)*(-1)^(k-1)*(56*k^2 -32*k +5)/((2*k-1)^2*binomial(3*k, k) *binomial(2*k, k)*k^3))), ", "))
(Magma) [Denominator((&+[(1/4)*(-1)^(k-1)*(56*k^2-32*k+5)/((2*k-1)^2*Binomial(3*k, k)*Binomial(2*k, k)*k^3): k in [1..n]])): n in [1..30]]; // G. C. Greubel, Oct 08 2018
(GAP) List(List([1..10], n->Sum([1..n], k->(1/4)*(-1)^(k-1)*(56*k^2-32*k+5)/((2*k-1)^2*Binomial(3*k, k)*Binomial(2*k, k)*k^3))), DenominatorRat); # Muniru A Asiru, Oct 09 2018
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CROSSREFS
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KEYWORD
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nonn,frac
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AUTHOR
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STATUS
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approved
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