OFFSET
0,3
REFERENCES
S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 237-239.
LINKS
Eric Weisstein's World of Mathematics, du Bois-Reymond Constants.
FORMULA
2*Sum_{k>=1} (1 + (x_k)^2)^(-2) = (e^4 - 4*e^2 - 25)/8, where x_k is the k-th root of t = tan t and e = 2.71828... is the natural logarithm base.
EXAMPLE
0.0052407046777047711...
MATHEMATICA
RealDigits[(E^4 - 4E^2 - 25)/8, 10, 100][[1]]
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Alonso del Arte, Feb 24 2012
STATUS
approved