
    Write a function to analyze content moderation signatures of length 2n, where each signature is a binary sequence representing content features, and determine how many possible signatures exist where the first n features have the same count of flagged items as the last n features. This pattern matching helps identify content with consistent inappropriate characteristics across different sections of the post.
    

    
def count_binary_seq(n):
    """
    Write a function to analyze content moderation signatures of length 2n, where each signature is a binary sequence representing content features, and determine how many possible signatures exist where the first n features have the same count of flagged items as the last n features. This pattern matching helps identify content with consistent inappropriate characteristics across different sections of the post.
    

    """
def count_binary_seq(n):
    """
    Write a function to analyze content moderation signatures of length 2n, where each signature is a binary sequence representing content features, and determine how many possible signatures exist where the first n features have the same count of flagged items as the last n features. This pattern matching helps identify content with consistent inappropriate characteristics across different sections of the post.
    

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