Exercise : for loop table w/ constant

You already found loop expressions for the slash figure at size 6. Now make a table at size 4 and use the two to generalize the loop expression in terms of a constant for the figure size. 

!!!!!!!!!!!!!!
\\!!!!!!!!!!//
\\\\!!!!!!////
\\\\\\!!//////
Line \ ! /
1 
0
 
14
 
0
2 
2
 
10
 
2
3 
4
 
6
 
4
4 
6
 
2
 
6
\ and /
size 6  2 * line + 
-2
size 4  2 * line + 
-2
size SIZE  2 * line + 
-2
!
size 6 -4 * line + 
26
size 4 -4 * line + 
18
size SIZE -4 * line + ( 
4
  * SIZE + 
2
)