【简答题】已知数列{a n }中,a 1 =2,a n -a n-1 -2n=0(n≥2,n∈N). (1)写出a 2 、a 3 的值(只写结果)并求出数列{a n }的通项公式; (2)设 b n = 1 a n+1 + 1 a n+2 + 1 a n+3 +…+ 1 a 2n ,若对任意的n,当m∈[-1,1]时,不等式 t 2 -2mt+ 1 6 > b n 恒成立,求实数t的取值范围.
【判断题】Suppose that there exist two parameter values satisfying that moment conditions equal 0, then it is possible to obtain a consistent consistent GMM estimator (the model is not identified).