The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A145560 Denominators of partial sums of a certain alternating series of inverse central binomial coefficients. 2
 1, 12, 180, 5040, 8400, 831600, 75675600, 302702400, 15437822400, 293318625600, 248192683200, 74209612276800, 8388912692160, 964724959598400, 46628373047256000, 5781918257859744000, 10921401153735072000, 884633493452540832000, 621897345897136204896000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS See A145559 for the numerators, references and a W. Lang link. LINKS Robert Israel, Table of n, a(n) for n = 1..772 FORMULA a(n) = (1/2)*denominator(r(n)), with the rationals (in lowest terms) r(n) := Sum_{k=1..n} (-1)^(k+1)/(binomial(2*k,k)*k^2). EXAMPLE Rationals r(n) (in lowest terms): [1/2, 11/24, 167/360, 4667/10080, 7781/16800, 770269/1663200, 70095379/151351200,...]. MAPLE map(denom, ListTools:-PartialSums([seq(2*(-1)^(k+1)/(binomial(2*k, k)*k^2), k=1..30)])): # Robert Israel, Sep 24 2017 CROSSREFS Cf. A145557/A145558, A145559. Sequence in context: A001814 A327079 A013924 * A332960 A230345 A166773 Adjacent sequences: A145557 A145558 A145559 * A145561 A145562 A145563 KEYWORD nonn,easy AUTHOR Wolfdieter Lang Oct 13 2008 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 2 07:25 EDT 2023. Contains 363081 sequences. (Running on oeis4.)