\begin{pmatrix}
a+1 & a & a & ... & a & a \\
a & a+2 & a & ... & a & a \\
a & a & a+2^2 & ... & a & a \\
. . . . \\
. . . . \\
. . . . \\
a & a & a & ... & a+2^{n-1} & a \\
a & a & a & ... & a & a+2^n \\
\end{pmatrix}