A:线粒体
B:核糖体
C:叶绿体
D:线粒体、叶绿体
Running man is popular TV show that I want to see it every day.
设数列{an}的前n项和为Sn,且Sn=n2+2n
(Ⅰ)求数列{an}的通项公式;
(Ⅱ)证明{an}是等差数列.