Is there a way to select an action when a specific number is reached in a counter?

For example, if I write:
Code:
counter = 0

loophere:
 if counter = 21 then counter = 0

counter = counter + 1

pause 100

goto loophere
What I would like to do is along the lines of:

if counter = 2 or 4 or 6 or 8 or 10 then
led1 = 1
else
led1 = 0
endif

if counter = 12 or 14 or 16 or 18 or 20 then
led2 = 1
else
led2 = 0
endif

I know you can write individual lines such as:

if (counter = 2) OR (counter = 4) OR (counter = 6)...then

or

if counter = 2 then
led1 = 1
else
led1 = 0
endif

if counter = 4 then
led1 = 1
else
led1 = 0
endif


And so on, but that eats up too much space. Just looking for someone to point me in the right direction. It's late and I'm drawing a blank as to which method to use to save space, but still get it done.

Thanks,
Tony