OFFSET
0,2
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.22 Lenz-Ising constants, p. 400.
LINKS
Eric Weisstein's MathWorld, Digamma Function
FORMULA
sqrt(3)/(6*Pi)*psi'(1/6) - Pi/sqrt(3) - log(6), where psi' is the derivative of the digamma function.
EXAMPLE
-0.1764297331308024303442948047616703...
MATHEMATICA
Sqrt[3]/(6*Pi)*PolyGamma[1, 1/6] - Pi/Sqrt[3] - Log[6] // RealDigits[#, 10, 101]& // First
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Jean-François Alcover, May 28 2014
STATUS
approved