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A130547
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Numerators of 6*(sum(1/binomial(2*k,k),k=1..n)-1/3), n>=1.
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3
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1, 2, 23, 167, 253, 5581, 13201, 48413, 823063, 15638407, 1117033, 89921239, 256917887, 60848977, 134111147453, 4157445588203, 1385815197541, 9700706385439, 358926136286437, 358926136292897, 474708760905697
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OFFSET
| 1,2
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COMMENTS
| Denominators are given by A130548.
The partial sums (in lowest terms) r(n):= 6*(sum(1/binomial(2*k,k),k=1..n)-1/3) tend, for n->infinity to 4*Pi*sqrt(3)/9, which is approximately 2.418399153.
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REFERENCES
| L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 89, Exercise (with a misprint).
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LINKS
| W. Lang, Rationals and limit.
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FORMULA
| a(n)=numer(r(n)), n>=1, with the rationals defined above.
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CROSSREFS
| Sequence in context: A193981 A053299 A189977 * A200846 A198851 A173341
Adjacent sequences: A130544 A130545 A130546 * A130548 A130549 A130550
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KEYWORD
| nonn,frac,easy
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AUTHOR
| Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de) Jul 13 2007
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