n = 5
for i in range(n-1):
print(i)
result: 0123
for i in range(n-1):
for j in range(n-i):
print(i)
result: 00000 1111 222 33
for i in range(n-1):
for j in range(n-i):
print(j)
result: 01234 0123 012 01
for i in range(n-1):
for j in range(n-i):
print(i+j)
result: 01234 1234 234 34