1.问题的提出今年一月底我校组织了高三调研考试,其中数学试卷倒数第二题是数列题,题目如下:已知数列{an}满足an=2an-1+2n-1(n≥2),且a4=81.(1)求数列的前三项a1,a2,a3; 1. Questions raised At the end of January this year, our school organized a senior high school examinations exam, in which the penultimate math test questions is a series of questions, the title is as follows: The known sequence {an} satisfy an = 2an-1 + 2n-1 ), And a4 = 81. (1) Find the first three terms a1, a2, a3;