if integer k is equal to the sum of all even multiples of 15 between 390 and 615 , what is the greatest prime factor of k ?
import math
n0 = 15.0
n1 = 390.0
n2 = 615.0
t0 = n2 / n0
t1 = n1 / n0
t2 = math.floor(t0)
t3 = math.floor(t1)
t4 = n0 * t2
t5 = n0 * t3
t6 = t4 - t5
t7 = t6 / n0
t8 = t7 + 1.0
answer = t8 / 2.0
print(answer)