12. Arrange the numbers of Pascal's Triangle aligned to the far left as follows:

The numbers in the diagonal direction connected by arrows are referred to as a diagonal, for example, the first diagonal is “ $1 \leftarrow 1$ ”, the second diagonal is “ $1 \longleftrightarrow \rightarrow 2$ ”, and the third diagonal is “ $1 \longleftrightarrow 3 \longleftrightarrow \rightarrow 1$ ”.
What is the sum of all the numbers on the 13th diagonal?
【Analysis】Find the pattern
The sums are $2,3,5,8,13,21,34,55,89,144,233,377,610 ; \ldots .$. (Notice that each subsequent number is the sum of the previous two)
The thirteenth sum is 610.