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#27808963-8434-4fd7-91f8-eb17de0b52a1基础填空题数列求和方法数列

3.(2023•全国二模)已知数列{an}\{a_{n}\}满足an=12n(n+1)a_{n}=\frac{1}{2n(n+1)},数列{an}\{a_{n}\}的前nn项和为TnT_{n},若Tn>nλn2+4n+19(λR)T_{n}>\frac{n\lambda }{{n^2}+4n+19}(\lambda \in {R})对任意nNn\in N^{*}恒成立,则λ\lambda的取值范围是((  ))