How much length of a very thin wire is required to obtain a solenoid of length l0 and inductance L?

Suppose solenoid has N turns, each of radius r and length of wire is l.Its self-inductance, L=μ0N2Al0=μ0N2πr2l0                  ….(i)Also, length of the wire, l=N×2 πr ⇒N2r2=l24π2                                                                 … (ii)From equations (i) and (ii),  l=4πLl0μ0