Help me to correct this code Matrix pattern

Question

Print the following pattern for the given number of rows.
Pattern for N = 5
1 2 3 4 5
11 12 13 14 15
21 22 23 24 25
16 17 18 19 20
6 7 8 9 10

My code-
n = int(input())
upper = int(n/2)+1
lower = n - upper
start_i_lower = 0

for i in range(0, upper):
if i != 0:
i = i + i
start = n*i + 1
end = start + n

for j in range(start, end):
print(j, end =" ")
start_i_lower = i
print()

start_i_lower -= 1

for i in range(0, lower):
if(n%2 == 0):
start_i_lower -= 1

start = n*(start_i_lower-1) + 1
end = start + n

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

print()

Answer 1

What if it's 6? Please give more examples.

Answer 2

Example if test case is:
2
Output
1 2
3 4

for 4
Output
1 2 3 4
9 10 11 12
13 14 15 16
5 6 7 8

And
for 8
Output
1 2 3 4 5 6 7 8
17 18 19 20 21 22 23 24
33 34 35 36 37 38 39 40
49 50 51 52 53 54 55 56
57 58 59 60 61 62 63 64
41 42 43 44 45 46 47 48
25 26 27 28 29 30 31 32
9 10 11 12 13 14 15 16

Answer 3

I still don't understand how the return-sequence works; what factor determines it?