先求和
lim(n->∞)[(1+3+5+.(2n+1)]/n^2]^(3-2n)
=lim(n->∞)[(n+1)^2/n^2]^(3-2n)
=lim(n->∞)(1+1/n)^(6-4n)
=lim(n->∞)(1+1/n)^(-4n)*lim(n->∞)(1+1/n)^6
=e^(-4)