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 A130414 Denominators of partial sums for a series for Pi/3. 2
 1, 18, 45, 1260, 945, 20790, 135135, 1081080, 765765, 87297210, 43648605, 4015671660, 5019589575, 30117537450, 436704293025, 216605329340400, 13537833083775, 27075666167550, 500899824099675, 2003599296398700 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The numerators are given in A130413. For the rationals r(n) see A130413 and the W. Lang link given there. LINKS Robert Israel, Table of n, a(n) for n = 0..1000 FORMULA a(n) = denominator(r(n)), n>=0, with the rationals defined in A130413. MAPLE f:= n -> denom(1+ (4/3)*add(((-1)^(j+1))/((2*j+1)*((2*j+1)^2-1)), j=1..n)): map(f, [\$0..20]); # Robert Israel, Jul 27 2015 CROSSREFS Sequence in context: A179896 A075284 A057444 * A108642 A250784 A250731 Adjacent sequences: A130411 A130412 A130413 * A130415 A130416 A130417 KEYWORD nonn,frac,easy AUTHOR Wolfdieter Lang, Jun 01 2007 STATUS approved

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Last modified January 27 05:49 EST 2023. Contains 359836 sequences. (Running on oeis4.)