Question

Given the arithmetic sequence `a_n=4+8(n-1)`, what is the domain for `n`?

Answer 1

Domain of `n` is `NN`, the set of natural numbers.

Explanation:

In any sequence, arithmetic, geometric, or harmonic or any other,

`n` represents number of terms, i.e. starting fromm `a_1`, then `a_2` and so on till say `a_n`, which is `n^(th)` term.

As `n` is used to count number of terms, it can take values of only natural numbers.

Hence domain of `n` is `NN`, the set of natural numbers.

Here too `n in NN`.