lesson_6_ex_1_17_18

# -*- coding: utf-8 -*-
"""
Created on Mon Apr 16 18:23:58 2018

@author: 07sta
"""
#compute the S = 3*4*5 + 4*5*6 + ... + 23*24*25 + 1896
s = 1896
for i in range(3,24):
    s = s + i*(i+1)*(i+2)
print s