sum = (n + 1) * (2 * x + n * n) / 2
for _ in range(1): sum = (n + 1) * (2 * x + n * n) / 2
sum = 1for x in ((n + 1), (2 * x + n * n), 0.5): sum *= x
x + (x+n) + (x+2n) + …+(x+n2);