∴f(n)=(2n? 1)2? (4n? 3)4n? 3,
∴f(n)=4n2? 8n+44n? 3= 14? 16n2? 32n+ 164n? 3= 14? (4n? 3)2? 2(4n? 3)+ 14n? 3= 14? [(4n-3)+ 14n? 3-2]
T= 14n? 3,
∵n≥2, ∴ t ∈ (0, 15), y= 14(t+ 1t-2) in t ∈ (0, 15).
When t= 15, that is, n=2, there is a minimum value, and f (2) = 45.
So the answer is: 45.