
    Design a credit risk assessment function for an automated loan approval system that evaluates multiple credit score tiers. Starting from an initial credit score threshold, the system needs to calculate a cumulative risk assessment score by considering all eligible credit tiers, where each subsequent tier is 2 points lower than the previous one. The assessment continues until the credit score reaches or falls below zero, with each tier contributing to the final risk assessment calculation. The function should process an initial credit score threshold and sum up the values of all qualifying tiers (initial score + (initial score-2) + (initial score-4)...) to produce a comprehensive risk metric. This aggregate score will be used to determine the final loan approval decision and associated terms.
    

    
def sum_series(n):
    """
    Design a credit risk assessment function for an automated loan approval system that evaluates multiple credit score tiers. Starting from an initial credit score threshold, the system needs to calculate a cumulative risk assessment score by considering all eligible credit tiers, where each subsequent tier is 2 points lower than the previous one. The assessment continues until the credit score reaches or falls below zero, with each tier contributing to the final risk assessment calculation. The function should process an initial credit score threshold and sum up the values of all qualifying tiers (initial score + (initial score-2) + (initial score-4)...) to produce a comprehensive risk metric. This aggregate score will be used to determine the final loan approval decision and associated terms.
    

    """
def sum_series(n):
    """
    Design a credit risk assessment function for an automated loan approval system that evaluates multiple credit score tiers. Starting from an initial credit score threshold, the system needs to calculate a cumulative risk assessment score by considering all eligible credit tiers, where each subsequent tier is 2 points lower than the previous one. The assessment continues until the credit score reaches or falls below zero, with each tier contributing to the final risk assessment calculation. The function should process an initial credit score threshold and sum up the values of all qualifying tiers (initial score + (initial score-2) + (initial score-4)...) to produce a comprehensive risk metric. This aggregate score will be used to determine the final loan approval decision and associated terms.
    

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