Given an integer `n` (in base `10`) and a base `k`, return the sum of the digits of `n` after converting `n` from base `10` to base `k`.

After converting, each digit should be interpreted as a base `10` number, and the sum should be returned in base `10`.

Example 1:

    Input: n = 34, k = 6
    Output: 9
    Explanation: 34 (base 10) expressed in base 6 is 54. 5 + 4 = 9.

Example 2:

    Input: n = 10, k = 10
    Output: 1
    Explanation: n is already in base 10. 1 + 0 = 1.

Constraints:

- `1 <= n <= 100`
- `2 <= k <= 10`