def pascal_triangle(rows: int) -> list:
    """
    https://oeis.org/A007318

    >>> pascal_triangle(4)
    [[1], [1, 1], [1, 2, 1], [1, 3, 3, 1], [1, 4, 6, 4, 1]]
    """
    res = [[1]]
    for _ in range(rows):
        row = res[-1]
        res.append([1, *map(sum, zip(row, row[1:])), 1])
    return res