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A205326
Decimal expansion of the sum of [0;n,n,n,...]^2 for n=1..infinity.
1
9, 1, 5, 5, 8, 7, 9, 1, 9, 9, 0, 1, 8, 1, 9, 7, 2, 5, 1, 9, 9, 8, 1, 6, 8, 5, 3, 8, 0, 3, 1, 9, 0, 0, 8, 9, 7, 3, 5, 3, 2, 0, 4, 6, 0, 1, 8, 9, 6, 6, 9, 0, 2, 4, 1, 2, 2, 7, 6, 9, 5, 1, 7, 0, 9, 6, 2, 1, 8, 2, 7, 0, 5, 5, 6, 4, 6, 5, 3, 3, 5, 9, 7, 5, 5, 3, 7
OFFSET
0,1
COMMENTS
This is the total area of all squares with sides parallel to the axes of the Cartesian coordinate system, the lower left vertex at (n,0) and the upper right vertex on f(x)=1/x for n=1..infinity.
FORMULA
Sum_{n>=1} 1/[n;n,n,...]^2.
Sum_{n>=1} 4/(n + sqrt(n^2 + 4))^2.
EXAMPLE
0.9155879199018197251998168538031900897353...
PROG
(PARI) zeta(2)+sumpos(n=1, 4/(n+sqrt(n^2+4))^2-1/n^2) \\ Charles R Greathouse IV, Jan 26 2012
CROSSREFS
Cf. A013661, A205325, continued fractions A001622, A014176, A098316, A098317, A098318.
Sequence in context: A258268 A143296 A198355 * A021526 A019791 A006752
KEYWORD
cons,nonn
AUTHOR
Martin Janecke, Jan 26 2012
EXTENSIONS
a(-5)-a(-86) from Charles R Greathouse IV, Jan 26 2012
STATUS
approved