Question for Angela Fajardo-2

In figure 1, there are $3$ triangles.
In figure 2, there are $8$ triangles.
In figure 3, there are $15$ triangles.
(For clarification):-
In figure 4, there are $24$ triangles.
In figure 5, there are $35$ triangles.

So, we see that in the ${n}^{\text{th}}$ figure, there are $(2 × \displaystyle \sum_{i=1}^n i) + n$ triangles.

So, in the ${2016}^{\text{th}}$ figure, there would be $(2 × \displaystyle \sum_{i=1}^{2016} i) + 2016$
= 4068288 triangles. $_\square$