
    A delivery fleet management system needs to calculate the total number of viable delivery routes throughout a day as traffic conditions worsen. Starting with an initial number of available routes, the system eliminates two routes at fixed intervals due to increasing traffic congestion and weather constraints. The calculation should sum up the number of available routes at each interval, beginning with the initial count and continuing until no viable routes remain. For example, if starting with 7 routes, the system would sum 7 + 5 + 3 + 1 to determine the total route options available across all time intervals. Write a function that performs this calculation to help optimize the fleet's delivery schedule throughout the day.
    

    
def sum_series(n):
    """
    A delivery fleet management system needs to calculate the total number of viable delivery routes throughout a day as traffic conditions worsen. Starting with an initial number of available routes, the system eliminates two routes at fixed intervals due to increasing traffic congestion and weather constraints. The calculation should sum up the number of available routes at each interval, beginning with the initial count and continuing until no viable routes remain. For example, if starting with 7 routes, the system would sum 7 + 5 + 3 + 1 to determine the total route options available across all time intervals. Write a function that performs this calculation to help optimize the fleet's delivery schedule throughout the day.
    

    """
def sum_series(n):
    """
    A delivery fleet management system needs to calculate the total number of viable delivery routes throughout a day as traffic conditions worsen. Starting with an initial number of available routes, the system eliminates two routes at fixed intervals due to increasing traffic congestion and weather constraints. The calculation should sum up the number of available routes at each interval, beginning with the initial count and continuing until no viable routes remain. For example, if starting with 7 routes, the system would sum 7 + 5 + 3 + 1 to determine the total route options available across all time intervals. Write a function that performs this calculation to help optimize the fleet's delivery schedule throughout the day.
    

    """
    if n < 1:
        return 0
    else:
        return n + sum_series(n - 2)