1+2nn\frac{1+2^{n}}{n}n1+2n
3n−112\frac{3^{n}-11}{2}23n−11
4n−57\frac{4^{n}-5}{7}74n−5
n−56\frac{n-5}{6}6n−5
1ln−92\frac{1 \ln -9}{2}21ln−9