Question $2$

A digit string is good if the digits $(0-$indexed$)$ at even indices are even and the digits at odd indices are prime $,$ or $7).$

For example, $"2582"$ is good because the digits $(2$ and $8)$ at even positions are even and the digits $(5$ and $2)$ at odd positions are prime.

However, $"3245"$ is not good because $3$ is at an even index but is not even.

Given an integer $n,$ return the total number of good digit strings of length $n.$

A digit string is a string consisting of digits $0$ through $9$ that may contain leading zeros. You have to use recursion to solve this question, nothing else.

Write the following code in python programming language.