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A130553 Numerators of partial sums for a series for 2*Pi*sqrt(3)/9. +0
2
1, 7, 6, 169, 1523, 133, 72623, 87149, 823077, 15638477, 46915441, 13834041, 224803169, 6936783521, 5587964507, 4157445593923, 12472336782289, 170187831339, 71785227258967, 153825486983593, 4905323862699739 (list; graph; listen)
OFFSET

1,2

COMMENT

Denominators are given in A130554.

The rational sequence r(n):=2*sum(1/(j*binomial(2*j,j)),j=1..n), n>=1, tends, in the limit n->infinity, to 2*Pi*sqrt(3)/9, which is approximately 1.209199577.

REFERENCES

L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 89, Exercise.

LINKS

W. Lang, Rationals and limit.

FORMULA

a(n)=numerator(r(n)), n>=1, with the rationals r(n) defined above and taken in lowest terms.

EXAMPLE

Rationals r(n): [1, 7/6, 6/5, 169/140, 1523/1260, 133/110, 72623/60060,...].

CROSSREFS

Adjacent sequences: A130550 A130551 A130552 this_sequence A130554 A130555 A130556

Sequence in context: A073112 A070425 A038272 this_sequence A002394 A105167 A109938

KEYWORD

nonn,frac,easy

AUTHOR

Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de) Jul 13 2007

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Last modified October 6 12:54 EDT 2008. Contains 144667 sequences.


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