
    Write a function to determine how many possible patient monitoring sequences exist where each sequence consists of 2n vital sign readings (1 for concerning, 0 for normal), and the count of concerning vital signs in the first n readings matches the count in the last n readings. This pattern helps identify whether a patient's condition has remained similarly stable or unstable across two consecutive monitoring periods.
    

    
def count_binary_seq(n):
    """
    Write a function to determine how many possible patient monitoring sequences exist where each sequence consists of 2n vital sign readings (1 for concerning, 0 for normal), and the count of concerning vital signs in the first n readings matches the count in the last n readings. This pattern helps identify whether a patient's condition has remained similarly stable or unstable across two consecutive monitoring periods.
    

    """
def count_binary_seq(n):
    """
    Write a function to determine how many possible patient monitoring sequences exist where each sequence consists of 2n vital sign readings (1 for concerning, 0 for normal), and the count of concerning vital signs in the first n readings matches the count in the last n readings. This pattern helps identify whether a patient's condition has remained similarly stable or unstable across two consecutive monitoring periods.
    

    """
    nCr = 1
    res = 1
    for r in range(1, n + 1):
        nCr = nCr * (n + 1 - r) / r
        res += nCr * nCr
    return res