Iterating within one list alone and printing a descendin pattern

n = int(input("Enter the Starting Row of Numbers : "))
str1, L1 = "", [1, 2, 3, 4, 5, 6, 7, 8, 9]
j, start = 0, 0

for i in L1:
    str1 += str(i)

while n >= 1:
    end = start+n

    if end > len(str1):
        req_str = str1[start:]
        new_n = n-len(req_str)
        new_start = 0
        req_str += str1[new_start:new_start+new_n]

    else:
        req_str = str1[start:end]

    print(req_str)

    j += 1
    n -= 1
    start = str1.index(req_str[-1]) + 1