
    Design a function that determines the number of unique ways to organize user interest categories into event recommendation groups, where each category must be assigned to exactly one group and no groups can be empty. Given n distinct user interest categories, calculate how many different arrangements of recommendation groups are possible to optimize event suggestions for the social networking platform.
    

    
def bell_number(n):
    """
    Design a function that determines the number of unique ways to organize user interest categories into event recommendation groups, where each category must be assigned to exactly one group and no groups can be empty. Given n distinct user interest categories, calculate how many different arrangements of recommendation groups are possible to optimize event suggestions for the social networking platform.
    

    """
def bell_number(n):
    """
    Design a function that determines the number of unique ways to organize user interest categories into event recommendation groups, where each category must be assigned to exactly one group and no groups can be empty. Given n distinct user interest categories, calculate how many different arrangements of recommendation groups are possible to optimize event suggestions for the social networking platform.
    

    """
    bell = [[0 for i in range(n + 1)] for j in range(n + 1)]
    bell[0][0] = 1
    for i in range(1, n + 1):
        bell[i][0] = bell[i - 1][i - 1]
        for j in range(1, i + 1):
            bell[i][j] = bell[i - 1][j - 1] + bell[i][j - 1]
    return bell[n][0]