The first four terms of a sequence are
T1 = 12 T2 = 12 + 22 T3 = 12 + 22 + 32 T4 = 12 + 22 + 32 + 42.
(a) The nth term is given by Tn =1/6n(n + 1)(2n + 1).
(b) A new sequence is formed as follows.
U1 = T2 – T1 U2 = T3 – T2 U3 = T4 – T3
Q. Write down a formula for the nth term, Un
