Baluteshih is doing a fake uniformly accelerated motion on a number line.
He starts at $x_0$.
The initial velocity is $v_0$.
The acceleration is $a$.
And he do this motion last for $t$ seconds.

This motion is different from normal uniformly accelerated motion.
At every second, he move $v$ units.
And then his $v$ will increase $a$.

Calculate the final position after he finish this motion.

For example:
Baluteshih starts at $5$ (which is $x_0$).
And his initial velocity is $3$ (which is $v_0$).
The acceleration is $2$ (which is $a$).
And $t=4$.

At beginning, let $v=v_0=3$
After $1$ second, he will stand on $8$, then $v$ increases $2$.($v\Rightarrow5$)
After $2$ seconds, he will stand on $13$, $v$ increases $2$.($v\Rightarrow7$)
After $3$ seconds, he will stand on $20$, $v$ increases $2$.($v\Rightarrow9$)
After $4$ seconds, he will stand on $29$.

After he finished this motion, he stand on $29$, so the answer is $29$.