数列｛an｝满足a1=1,且an=an-1+3n-2,求an

a1=1an = an-1 + 3n -2an-1= an-2 + 3(n-1)-2。。。a2 = a1 + 3*2 -2左右分别相加an = a1 + 3*(n+n-1+。。。+2) - 2*(n-1)an = 1 + 3*(n+2)*(n-1)/2 - 2*(n-1)= 1 + (n-1)(3n/2+1)