
    Design a function that calculates the total number of sensor checkpoints required for the nth maintenance zone in a public transit vehicle inspection system, where each zone expands hexagonally from the vehicle's center point. The number of checkpoints follows a hexagonal sequence pattern, ensuring comprehensive coverage as inspection zones grow outward from the central diagnostic point.
    

    
def hexagonal_num(n):
    """
    Design a function that calculates the total number of sensor checkpoints required for the nth maintenance zone in a public transit vehicle inspection system, where each zone expands hexagonally from the vehicle's center point. The number of checkpoints follows a hexagonal sequence pattern, ensuring comprehensive coverage as inspection zones grow outward from the central diagnostic point.
    

    """
def hexagonal_num(n):
    """
    Design a function that calculates the total number of sensor checkpoints required for the nth maintenance zone in a public transit vehicle inspection system, where each zone expands hexagonally from the vehicle's center point. The number of checkpoints follows a hexagonal sequence pattern, ensuring comprehensive coverage as inspection zones grow outward from the central diagnostic point.
    

    """
    return n * (2 * n - 1)