
    In a bank's fraud detection system, design a function that calculates the number of transaction pattern checkpoints needed at the nth stage of analysis, where each stage follows a decagonal progression to maintain optimal fraud detection coverage. The resulting checkpoint count must follow the decagonal number sequence to ensure consistent pattern recognition across all customer transaction analyses.
    

    
def is_num_decagonal(n):
    """
    In a bank's fraud detection system, design a function that calculates the number of transaction pattern checkpoints needed at the nth stage of analysis, where each stage follows a decagonal progression to maintain optimal fraud detection coverage. The resulting checkpoint count must follow the decagonal number sequence to ensure consistent pattern recognition across all customer transaction analyses.
    

    """
def is_num_decagonal(n):
    """
    In a bank's fraud detection system, design a function that calculates the number of transaction pattern checkpoints needed at the nth stage of analysis, where each stage follows a decagonal progression to maintain optimal fraud detection coverage. The resulting checkpoint count must follow the decagonal number sequence to ensure consistent pattern recognition across all customer transaction analyses.
    

    """
    return 4 * n * n - 3 * n