What is the van't Hoff factor for a compound which undergoes tetramerization in an organic solvent ?

 
In case of association i (van’t Hoff factor) is given by
i = 1 – (1- 1/n)α, where
n= number of molecules associates = 4 (here),
α = fraction of molecules associates
 
i = 1 – (1- ¼)α = 1 – ¾ α
if α be 1 (complete association), then
 
i= 1 – ¾ = ¼