def tri(n):
    if n == 0:
        return [1]
    my_tri = [1, 3]
    for i in range(2, n + 1):
        if i % 2 == 0:
            my_tri.append(i / 2 + 1)
        else:
            my_tri.append(my_tri[i - 1] + my_tri[i - 2] + (i + 3) / 2)
    return my_tri
from typing import List
def separate_paren_groups(paren_string: str) -> List[str]:
    result = []
    current_string = []
    current_depth = 0
    for c in paren_string:
        if c == '(':
            current_depth += 1
            current_string.append(c)
        elif c == ')':
            current_depth -= 1
            current_string.append(c)
            if current_depth == 0:
                result.append(''.join(current_string))
                current_string.clear()
    return result