Kleinian integer

In mathematical cryptography, a Kleinian integer is a complex number of the form $$m+n\frac{1+\sqrt{-7}}{2}$$, with m and n rational integers. They are named after Felix Klein.

The Kleinian integers form a ring called the Kleinian ring, which is the ring of integers in the imaginary quadratic field $$\mathbb{Q}(\sqrt{-7})$$. This ring is a unique factorization domain.