A096950 Denominators of partial sums of series for 3*arctanh(1/3) = (3/2)*log(2).

1, 27, 405, 25515, 2066715, 7577955, 2659862205, 71816279535, 3662630256285, 626309773824735, 2415766270466835, 166687872662211615, 7500954269799522675, 1822731887561284010025, 52859224739277236290725

Offset

0,2

Comments

Numerators are given in A096949.

Links

Table of n, a(n) for n=0..14.

Formula

a(n)=denominator(A(n)) with the rational number A(n):= sum(((1/3)^(2*k))/(2*k+1), k=0..n) in lowest terms.

Example

n=10: A096949(10)/2415766270466835 = 2511722368895123/2415766270466835 = 1.039720770838... approximates 3*arctanh(1/3)= 1.039720770840...

Crossrefs

Sequence in context: A036222 A022655 A155988 * A307911 A125484 A022751

Adjacent sequences: A096947 A096948 A096949 * A096951 A096952 A096953

Keyword

nonn,easy,frac

Author

Wolfdieter Lang, Jul 16 2004

Status

approved