A242001 Decimal expansion of the two-dimensional series sum_{i,j=-infinity..infinity} (-1)^(i+j)/(i^2+(3*j+1)^2).

2, 6, 6, 1, 5, 7, 0, 0, 1, 8, 7, 1, 6, 3, 7, 5, 6, 2, 5, 9, 6, 4, 1, 5, 5, 1, 2, 4, 4, 6, 5, 7, 9, 6, 8, 9, 7, 2, 6, 2, 1, 7, 9, 9, 9, 3, 9, 5, 1, 2, 7, 7, 5, 5, 7, 1, 2, 5, 0, 7, 7, 5, 4, 0, 6, 1, 3, 0, 1, 5, 8, 1, 2, 0, 9, 2, 7, 9, 2, 4, 1, 3, 4, 5, 4, 5, 2, 4, 0, 7, 3, 1, 1, 9, 7, 3, 4, 2, 6, 0, 0, 4, 3, 4

Offset

0,1

Links

Table of n, a(n) for n=0..103.

Steven R. Finch, Errata and Addenda to Mathematical Constants. p. 8.

Formula

(2*Pi/9)*log(2*(sqrt(3) - 1)).

Example

0.2661570018716375625964155124465796897262179993951277557125...

Mathematica

RealDigits[(2*Pi/9)*Log[2*(Sqrt[3] - 1)], 10, 104] // First

Crossrefs

Sequence in context: A110666 A200485 A201318 * A175994 A372985 A340212

Adjacent sequences: A241998 A241999 A242000 * A242002 A242003 A242004

Keyword

nonn,cons,easy

Author

Jean-François Alcover, Aug 11 2014

Status

approved