已知数列an满足:a1=1,a2=6,an+2=-an

已知数列{an}满足a1=1,a2=-13,an+2-2an+1+an=2n-6 已知数列{an}满足a1=1，a2=-13，an+2-2an+1+an=2n-6 已知数列an满足an=1+2+...+n,且1/a1+1/a2+...+1/an 已知数列{an}满足a1=1,a2=3,an+2=3an+1-2an求an 已知数列{an}满足a1=1，a2=2，an+2=an+an+12，n∈N*． 已知数列an满足a1=1.a2=3,an+2=3an+1-2an 一直数列{An}满足A1=1/2,A1+A2+…+An=n^2An 已知数列{an}满足：a1+a2+a3+.+an=n^2,求数列{an}的通项an. 已知数列{an}满足a1=1,a2=2,an+2=(an+an+1)/2,n∈N*.令bn=an+1-an,证明{bn} 已知数列{an}满足a1+a2+a3+...+an=n^2+2n.(1)求a1,a2,a3,a4 关于数列极限的已知数列an满足a1=0 a2=1 an=(an-1+an-2)/2 求lim(n->无穷）an 已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an