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 A096949 Numerators of partial sums of series for 3*arctanh(1/3) = (3/2)*log(2). 2
 1, 28, 421, 26528, 2148803, 7878956, 2765513941, 74668877408, 3808112752813, 651187280816108, 2511722368895123, 173308843453994432, 7798897955430811787, 1895132203169713822916, 54958833891921780540589 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Denominators are given in A096950. From the series of log((1+x)/(1-x)) for x=1/3, i.e. for log(2) = 2*sum(((1/3)^(2*k+1))/(2*k+1),k=0..infty). LINKS FORMULA a(n)=numerator(A(n)) with the rational number A(n):= sum(((1/3)^(2*k))/(2*k+1), k=0..n) in lowest terms. EXAMPLE n=3: 26528/A096950(3) = 26528/25515 = 1.0397021... approximates 3*arctanh(1/3)= 1.039720771... CROSSREFS Sequence in context: A271793 A024213 A004415 * A093974 A121803 A022656 Adjacent sequences:  A096946 A096947 A096948 * A096950 A096951 A096952 KEYWORD nonn,easy,frac AUTHOR Wolfdieter Lang, Jul 16 2004 STATUS approved

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Last modified July 22 07:23 EDT 2019. Contains 325216 sequences. (Running on oeis4.)