Let S = 9 + 16 + 29 + 54 + 103 + ................. + Tn ...........(i)
S = 9 + 16 + 29 + 54 + 103 + ......... + Tn–1 +Tn ...........(ii)
(i) – (ii) ⇒ Tn = 9 + 7 + 13 + 25 + 49 + ................. + (Tn – Tn–1) ...........(iii)
Tn = 9 + 7 + 13 + 25 + 49 + ........... + (Tn–1–Tn–2) + (Tn – Tn–1) ...........(iv)