\begin{definition}[Definition:Amicable Triplet/Definition 2]
Let $m_1, m_2, m_3 \in \Z_{>0}$ be (strictly) positive integers.
$\tuple {m_1, m_2, m_3}$ are an '''amicable triplet''' {{iff}}:
:$\map {\sigma_1} {m_1} = \map {\sigma_1} {m_2} = \map {\sigma_1} {m_3} = m_1 + m_2 + m_3$
where $\sigma_1$ denotes the divisor sum function.
\end{definition}