def binary_search(lst, target, low=0, high=None):
    """Binary search recursively."""
    if high is None:
        high = len(lst) - 1
    if low > high:
        return -1
    mid = (low + high) // 2
    if lst[mid] == target:
        return mid
    elif lst[mid] > target:
        return binary_search(lst, target, low, mid-1)
    else:
        return binary_search(lst, target, mid+1, high)

print(binary_search([1, 3, 5, 7, 9], 7))

def binary_search_recursive(arr, low, high, target):
    """
    Performs a recursive binary search on a sorted array.

    Args:
        arr (list): The sorted list to search within.
        low (int): The lower bound of the current search space.
        high (int): The upper bound of the current search space.
        target: The element to search for.

    Returns:
        int: The index of the target element if found, otherwise -1.
    """
    if low > high:  # Base case: Search space is exhausted
        return -1

    mid = (low + high) // 2  # Calculate the middle index

    if arr[mid] == target:  # Target found at the middle
        return mid
    elif arr[mid] > target:  # Target is in the left half
        return binary_search_recursive(arr, low, mid - 1, target)
    else:  # Target is in the right half
        return binary_search_recursive(arr, mid + 1, high, target)

# Example Usage:
sorted_list = [1, 5, 9, 13, 17, 21, 25, 29]
target_element_found = 17
target_element_not_found = 10

# Search for an element present in the list
index_found = binary_search_recursive(sorted_list, 0, len(sorted_list) - 1, target_element_found)
if index_found != -1:
    print(f"Element {target_element_found} found at index: {index_found}")
else:
    print(f"Element {target_element_found} not found.")

# Search for an element not present in the list
index_not_found = binary_search_recursive(sorted_list, 0, len(sorted_list) - 1, target_element_not_found)
if index_not_found != -1:
    print(f"Element {target_element_not_found} found at index: {index_not_found}")
else:
    print(f"Element {target_element_not_found} not found.")