where is an Integer or Rational Number, is the Inverse Tangent, and
is the Inverse Cotangent. Gregory numbers arise in the determination of Machin-Like Formulas.
Every Gregory number can be expressed uniquely as a sum of s where the s are Størmer
Conway, J. H. and Guy, R. K. ``Gregory's Numbers'' In The Book of Numbers. New York:
Springer-Verlag, pp. 241-242, 1996.
© 1996-9 Eric W. Weisstein