A082690 Denominator of n*sum(k=1,(-1)^(k+1)/(n+k)).

2, 6, 20, 210, 504, 4620, 51480, 90090, 1361360, 23279256, 21162960, 446185740, 2059318800, 5736673800, 155272637520, 9025222055850, 8494326640800, 8022419605200, 281206918792800, 267146572853160, 10431437606647200

Offset

1,1

Links

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

Formula

limit n ->infinity n*sum(k=1, (-1)^(k+1)/(n+k)) = 1/4

Crossrefs

Cf. A082689 (numerators).

Sequence in context: A074008 A156334 A296519 * A104861 A074859 A162682

Adjacent sequences: A082687 A082688 A082689 * A082691 A082692 A082693

Keyword

frac,nonn

Author

Benoit Cloitre, Apr 12 2003

Status

approved