数列\(\{a _{n} \}\)中，\(a _{1} =1\)，\(a_{n+1}= \begin{cases} a_{n}+1, \dfrac {n}{4}∉N^{*} \\ a_{n}, \dfrac {n}{4}∈N^{*}\end{cases}\)，设\(\{a _{n} \}\)的前\(n\)项和为\(S _{n}\)，若\(S_{4n}\leqslant λ\cdot 2^{n-1}\)恒成立，则实数\(λ\)的取值范围是______．