A242597 One half of the denominators of the partial sums of dilog(1/2).

1, 8, 72, 1152, 28800, 4800, 117600, 30105600, 812851200, 812851200, 98354995200, 393419980800, 66487976755200, 33243988377600, 8310997094400, 17020922049331200, 4919046472256716800, 1639682157418905600, 591925258828224921600, 295962629414112460800, 295962629414112460800

Offset

1,2

Comments

The numerator sequence is A242596. See the comment there for details and the Abramowitz-Stegun link and the Jolley reference.

Links

Table of n, a(n) for n=1..21.

Formula

a(n) = denominator(r(n))/2 with the rational r(n) := sum(1/(k^2*2^k), k=1..n) in lowest terms.

Example

r(10^k), for k=1..3: .5000000000, .5822335189, .5822405265, .5822405265 (maple 10 digits). To be compared with the limit 0.58224052646... given in A076788.

Crossrefs

Cf. A242596, A076788, A243456.

Sequence in context: A129103 A111812 A138433 * A339469 A241032 A001799

Adjacent sequences: A242594 A242595 A242596 * A242598 A242599 A242600

Keyword

nonn,easy

Author

Wolfdieter Lang, Jun 16 2014

Status

approved