The function defined by
, where is the Tangent. The Maclaurin Series for cot
is

where is a Bernoulli Number.

It is known that, for , is rational only for .

**References**

Abramowitz, M. and Stegun, C. A. (Eds.). ``Circular Functions.'' §4.3 in
*Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.*
New York: Dover, pp. 71-79, 1972.

Spanier, J. and Oldham, K. B. ``The Tangent and Cotangent Functions.''
Ch. 34 in *An Atlas of Functions.* Washington, DC: Hemisphere, pp. 319-330, 1987.

© 1996-9

1999-05-25