.
For your info :
(a) a^n means
, and is used ONLY for this purpose: to show raising in degree "n".
For example, 2^2 =
= 4; 3^2 =
= 9.
(b) If you want to show the n-th term of a progression / (of a sequence), write a[n] or a(n).
We, the tutors, will read it as
.