Pascal's Triangle

def pascal_triangle() :
    n = int(input("Enter the number of rows : "))

    a = []

    for i in range(n) :
        a.append([])
        a[i].append(1)

        for j in range(1 , i) :
            a[i].append(a[i-1][j-1] + a[i-1][j])

        if n != 0 :
            a[i].append(1)

    for i in range(n) :
        print((" "*(n-i)) , end = "")

        for j in range((i+1)) :
            print('{0:6}'.format(a[i][j]) , end = "")
        print()

pascal_triangle()