Matrices and Determinants: JEE Main 2021 Mathematics question

Let $A = \left( {\matrix{ 1 & { - 1} & 0 \cr 0 & 1 & { - 1} \cr 0 & 0 & 1 \cr } } \right)$ and B = 7A²⁰ $-$ 20A⁷ + 2I, where I is an identity matrix of order 3 $\times$ 3. If B = [b_ij], then b₁₃is equal to _____________.