Once you get to 128 64 32 16 in the first row then get a 128 in the second row and add it with 128 of first row. Next step is to get 64 in the second row and add it to 64 of first row. do it with 32 and 16 as well. Now you have 256 128 64 32 in first row. in the third step again do it with 128 then 64 then with 32. You'll get 512 64 32 and an empty space in the first row. Get 32 in the first row first. then keep repeating it.