
    Given a social network with n distinct user interests, determine the number of different ways these interests can be grouped into recommendation clusters, where each interest must belong to exactly one cluster and empty clusters are not allowed. Each unique clustering arrangement represents a different strategy for organizing event recommendations and connecting users with shared interests.
    

    
def bell_number(n):
    """
    Given a social network with n distinct user interests, determine the number of different ways these interests can be grouped into recommendation clusters, where each interest must belong to exactly one cluster and empty clusters are not allowed. Each unique clustering arrangement represents a different strategy for organizing event recommendations and connecting users with shared interests.
    

    """
def bell_number(n):
    """
    Given a social network with n distinct user interests, determine the number of different ways these interests can be grouped into recommendation clusters, where each interest must belong to exactly one cluster and empty clusters are not allowed. Each unique clustering arrangement represents a different strategy for organizing event recommendations and connecting users with shared interests.
    

    """
    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]