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A130550 Denominators of partial sums for a series for 2*Zeta(2)/3 = (Pi^2)/9. 3
1, 12, 180, 1008, 8400, 118800, 75675600, 302702400, 15437822400, 26665329600, 3226504881600, 5708431713600, 964724959598400, 964724959598400, 46628373047256000, 340112838697632000, 98292610383615648000 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

Numerators are given in A130549.

For the rationals r(n):= 2*sum(1/(j^2*binomial(2*j,j)),j=1..n), n>=1, the van der Poorten reference and a W. Lang link see A130551.

REFERENCES

C. Elsner, On recurrence formulae for sums involving binomial coefficients, Fib. Q., 43 (No. 1, 2005), 31-45.

FORMULA

a(n)=denominator(r(n)), n>=1.

Denominator of (2/3)* Sum_{i=1..n} 1/(i^2*C(2*i,i)). - Wolfdieter Lang, Oct 07 2008

CROSSREFS

Cf. A112099, A112100, A112102, A112103, A130549.

Sequence in context: A099930 A052208 A045952 * A073975 A069685 A000515

Adjacent sequences:  A130547 A130548 A130549 * A130551 A130552 A130553

KEYWORD

nonn,frac,easy

AUTHOR

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

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Last modified February 13 22:36 EST 2012. Contains 205567 sequences.