Pascal's Triangle

pascal.py

def pascal(n):
    L = n + n - 1
    rows = []
    row = [1]
    rows.append(row)
    while len(rows) < n:
        row_cat = [0] + row + [0]
        row = [row_cat[i] + row_cat[i+1] for i in range(len(row_cat)-1)]
        rows.append(row)
    for row_idx, row in enumerate(rows):
        print(" "*(n-row_idx), end="")
        print(" ".join([str(r) for r in row]))
        
        
# pascal(6)
#       1
#      1 1
#     1 2 1
#    1 3 3 1
#   1 4 6 4 1
#  1 5 10 10 5 1