There are altogether 31 rows. The $16^{\mathbb{1 1}}$ row is the middle row, which has 64 seats.
The $15^{\text {th }}$ row has $64-2=62$ seats.
The $14^{\text {th }}$ row has $64-2 \times 2=60$ seats.
$\qquad$
The $1^{\text {st }}$ row has $64-2 \times 15=34$ seats.
Total number of seats $=\frac{n}{2}[2 a+(n-1) d]=\frac{31}{2}[2 \cdot 34+(31-1) \cdot 2]=1984$
$$
\begin{aligned}
\text { Method } 2 \text { Total number of seats } & =\left(1^{\text {st }} \text { row }+31^{\text {st }} \text { row }\right)+\left(2^{\text {nd }} \text { row }+30^{\text {th }} \text { row }\right)+\ldots+16^{\text {th }} \text { row } \\
& =(64+64)+(64+64)+\ldots+64(31 \text { terms })=1984
\end{aligned}
$$
I1.4 There are $c$ rows in a concert hall and each succeeding row has two more seats than the previous row. If the middle row has 64 seats, how many seats does the concert have?