What is the recursive definition for 5 9 13 17 21?

The recursive definition for the sequence 5, 9, 13, 17, 21 is:

* Base case: The first term of the sequence is 5.

* Recursive step: Each subsequent term is obtained by adding 4 to the previous term.

We can express this mathematically as:

* a₁ = 5

* a_n = a_n-1 + 4 for n > 1

This means:

* a₁ is the first term, which is 5.

* For any term after the first (n > 1), the value (a_n) is calculated by taking the previous term (a_n-1) and adding 4 to it.