Question 1167353
The only way this problem makes sense is if the top row contains 1 brick.
Otherwise, there is no way to know how many bricks we are starting with 
on the top row.  
The number of bricks in the x-th row, can be represented by an arithmetic sequence: a_x = a_1 + (x-1)*d, 
where d = the common difference = 1,
and a_1 = the first term = 1
The sum of the first x terms of an arithmetic sequence is:
S_x = (x/2)(a_1 + a_x) = (x/2)(1 + a_x)
But a_x = 1 + (x - 1) = x
Thus S_x = f(x) = (x/2)(1 + x) = x^2/2 + x/2