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A130554
Denominators of partial sums for a series for 2*Pi*sqrt(3)/9.
1
1, 6, 5, 140, 1260, 110, 60060, 72072, 680680, 12932920, 38798760, 11440660, 185910725, 5736673800, 4621209450, 3438179830800, 10314539492400, 140744203600, 59365905078480, 127212653739600, 4056670180362800
OFFSET
1,2
COMMENTS
Numerators are given in A130553.
For the rationals r(n) := 2*Sum_{j=1..n} 1/(j*binomial(2*j,j)), n >= 1, the A. Comtet reference and a W. Lang link see A130553.
FORMULA
a(n) = denominator(r(n)), n >= 1, with the rationals r(n) defined above.
PROG
(PARI) a(n) = denominator(2*sum(j=1, n, 1/(j*binomial(2*j, j)))); \\ Michel Marcus, Nov 09 2019
CROSSREFS
Cf. A130553 (numerators), A248897 (2*Pi*sqrt(3)/9).
Sequence in context: A223529 A189422 A266980 * A291067 A037054 A284740
KEYWORD
nonn,frac,easy
AUTHOR
Wolfdieter Lang, Jul 13 2007
STATUS
approved