A Gauss-Kummer series is defined, for complex numbers with
, by
|
(1)
| |||
|
(2)
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(OEIS A056981 and A056982), where
is a hypergeometric function and
is a binomial
coefficient. The series can be derived using Kummer's
quadratic transformation. The Gauss-Kummer series is closely related to the perimeter of an ellipse.