设a0=1a_0=1a0=1,an=(−1)n−1n22n−1C2n−2n−1a_n=\frac{(-1)^{n-1}}{n2^{2n-1}}C_{2n-2}^{n-1}an=n22n−1(−1)n−1C2n−2n−1
求证∑k=0nak∗an−k=0\sum_{k=0}^n a_k*a_{n-k}=0∑k=0nak∗an−k=0
设∑k=0[n2]Cn−kk=an\sum_{k=0}^{[\frac{n}{2}]}C^k_{n-k}=a_n∑k=0[2n]Cn−kk=an
求证an=an−1+an−2a_n=a_{n-1}+a_{n-2}an=an−1+an−2
