
    Write a function to determine the number of possible diagnostic sequences where the count of abnormal vital signs in the first half of the monitoring period equals the count in the second half, given that each period contains n readings and each reading is marked as either normal or abnormal. The total monitoring sequence length is 2n, where each vital sign status is represented as a binary value (0 for normal, 1 for abnormal).
    

    
def count_binary_seq(n):
    """
    Write a function to determine the number of possible diagnostic sequences where the count of abnormal vital signs in the first half of the monitoring period equals the count in the second half, given that each period contains n readings and each reading is marked as either normal or abnormal. The total monitoring sequence length is 2n, where each vital sign status is represented as a binary value (0 for normal, 1 for abnormal).
    

    """
def count_binary_seq(n):
    """
    Write a function to determine the number of possible diagnostic sequences where the count of abnormal vital signs in the first half of the monitoring period equals the count in the second half, given that each period contains n readings and each reading is marked as either normal or abnormal. The total monitoring sequence length is 2n, where each vital sign status is represented as a binary value (0 for normal, 1 for abnormal).
    

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