Actually, if your M/2 isn't integer division (which I assume is the case from your use of ceil around it first), your 5x5 pyramid would look like this: 234

Actually, if your M/2 isn't integer division (which I assume is the case from your use of ceil around it first), your 5x5 pyramid would look like this: 23443 34554 45665 45665 34554 Using max_height - (abs(i - floor(M/2)) + abs(j - floor(N/2))) would give the properly-centered pyramid: 23432 34543 45654 34543 23432 Your max height should really be just max(ceil(M/2), ceil(N/2)) for a height of 3 going to 1 at the edges or floor(M/2) for 2 to 0. Using both Manhattan distances gives you an octagon-base pyramid (approximated to the square shape) when really you just want the max of both distances: max_height - max(abs(i - floor(M/2)), abs(j - floor(N/2))) gives: 11111 12221 12321 12221 11111 But this only works for square pyramids, using 3x5 you get: 12221 12321 12221 If you want a rectangle pyramid, use min manhattan distance from edge (don't need a max height then): 1 + min(i, N-i-1, j, M-j-1) gives: 11111 12221 11111 or for a 7x10 grid: 1111111111 1222222221 1233333321 1234444321 1233333321 1222222221 1111111111 Python 3 code for those who want to test themselves: N = 7 M = 10 for i in range(N): print("".join(str(1 + min(i,j,N-i-1,M-j-1)) for j in range(M)))