数列{Xn}满足X1=3/2,Xn+1={3Xn(n为奇数) Xn+N(n为偶数)} Yn=X2n-1+N + 1/2,n€N* 求证：数列{Yn}是等比数列

X(2n-1)=X(2n-2+1)
=X(2n-2)+2n-2
=X(2n-3+1)+2n-2
=3X(2n-3)+2n-2
可得：
Y(n)-n-1/2=3*(Y(n-1)-n+1/2)+2n-2=3Y(n-1)-n-1/2
Y(n)=3Y(n-1)