for i in range(5):
   for j in range(i + 1):
      print(j + 1, end="")
   print("")

1
12
123
1234
12345

start = 1
for i in range(5):
   for j in range(i + 1):
      print(start, end=" ")
      start += 1
print("")

1
2 3
4 5 6
7 8 9 10
11 12 13 14 15

start = 15
for i in range(5):
   for j in range(i + 1):
   print(start, end=" ")
   start -= 1
print("")

15
14 13
12 11 10
9 8 7 6
5 4 3 2 1