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A281070
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a(n) is the numerator of 6 * Sum_{k=0..n} ((k+1)/(n-k+1)^2) * (Catalan(k)/(2^(2*k+1)))^2.
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3
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3, 9, 109, 1037, 91027, 1540981, 447810157, 147053171, 503445581741, 16337573574319, 88973047698967, 3588920671411951, 2314594755016141847, 20685050199210758743, 2160689714871889935101, 121435710295138581181033, 16427863327419202412927713
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OFFSET
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0,1
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COMMENTS
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The series a(n)/A280723(n) is absolutely convergent to Pi.
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LINKS
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MATHEMATICA
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a[n_]=6(Sum[(1/(n-k+1)^2)((CatalanNumber[k])/(2^(2k+1)))^2(k+1), {k, 0, n}]); Numerator /@a/@ Range[0, 10]
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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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