User:Pentti Haukkanen/sandbox

In mathematics, a bi-unitary multiply perfect number is a variation of a perfect number.

Peter Hagis (1987) introduced the notion of bi-unitary multi k-perfect numbers. In fact, n is called a bi-unitary multi k-perfect number if σ^{∗∗}(n) = kn. A bi-unitary multiply perfect number is simply a bi-unitary multi k-perfect number for some positive integer k. Equivalently, bi-unitary multiply perfect numbers n are solutions of n divides σ^{∗∗}(n). A bi-unitary multi 3-perfect number is called a bi-unitary triperfect number.