target = 4
n = (target * 2) - 1
matrix = [[0] * n for _ in range(n)]
x, u, d, l, r = 1, 0, n - 1, 0, n - 1
c = target
while l < r and u < d:
  for j in range(l, r):
    matrix[u][j] = c
  for i in range(u, d):
    matrix[i][r] = c
  for j in range(r, l, -1):
    matrix[d][j] = c
  for i in range(d, u, -1):
    matrix[i][l] = c
  u, d, l, r, c = u + 1, d - 1, l + 1, r - 1, c - 1
if l == r:
  matrix[u][r] = c
print(matrix)