设数列｛bn｝,令bn=an/n则an=n*bna(n+1)=(n+1)*b(n+1)代入na(n+1)=(n+2)an得n*(n+1)*b(n+1)=(n+2)*n*bnb(n+1)/(n+2)=bn/(n+1)则｛bn/(n+1)｝是公比为1的等比数列即bn/(n+1)=b1/(1+1)=(a1/1)/(1+1)=3/2bn=(3/2)(n+1)a...