I have stumbled upon the following matrix
\begin{align} M = \begin{pmatrix} I& A&A\\ A& I &A\\ A&A&I \end{pmatrix}\,, \end{align}
where $I$ is the identity matrix and $A$ is defined as,
\begin{align} A = \begin{pmatrix} 1& a&a\\ a& 1 &a\\ a&a&1 \end{pmatrix}\,, \end{align}
with $a$ being a scalar. The structure of the block matrix $M$ mimics the structure of its blocks $A - I$ was wondering if matrices likes these have a particular name?