Explanation
Given that Sn = Sn-2 . (Sn-1 - 1)
Tn = Sn - Sn-1
Tn = Sn-2 . (Sn-1 - 1) - (Sn-3 . (Sn-2 - 1))
T3 = S1.(S2-1) - (S0.(S1-1)
T3 = 2.(3-1) - 1.(2-1)
T3 = 2(2) - 1(1)
T3 = 4-2
T3 = 3
T4 = S2.(S3-1) - (S1.(S2-1)
T4 =3.(-1) - 1.(2-1)
T4 = 2(2) - 1(1)
T4 = 4-2
T4 = 3
