A = 1 + 2 + 2^2 +......+ 100^2
A = 1.(2 - 1) + 2.(3 - 1) + 3.(4 - 1) +....+ 99.(100 - 1) + 100.(101 - 1)
A = 1.2 - 1.1 + 2.3 - 1.2 + 3.4 - 1.3 +...+99.100 - 1.99 + 100.101 - 1.100
A = (1.2 + 2.3 + 3.4 +...+ 99.100 + 100.101) - (1 + 2 + 3 +...+ 100)
A = [1.2.3 + 2.3.(4 - 1) + 3.4.(5 - 2)+...+ 100.101.(102 - 99) ] /3 + [(100 +1).100 /2]
A = [1.2.3 + 2.3.4 - 1.2.3 + 3.4.5 - 2.3.4 +....+ 100.101.102 - 99.10.101]/3 + 5050
A = 100.101.102/3 + 5050
A = 348450
