数列{an}满足:a1=2,an=an-1+2n-1(n≥2),则该数列的通项公式是 _ .
问题描述:
数列{an}满足:a1=2,an=an-1+2n-1(n≥2),则该数列的通项公式是 ___ .
答
∵数列{an}满足:a1=2,an=an-1+2n-1(n≥2),
∴an-an-1=2n-1(n≥2),
∴an=a1+a2-a1+a3-a2+…+an-an-1
=2+3+5+7+…+(2n-1)
=2+
(n-1)(3+2n-1) 2
=n2+1.
故答案为:an=n2+1.