引理:面向所有人$t\in\mathbb N$,$$\alpha_t:=\sup_{n>t}\frac{ln^{t+1}(n+1)}{\sum_{ell=t+1}^{n}\fracl{ell+1}\ln^t(\ell)}<\infty$$
证据提示:修复$t(美元)$你可以找到$N\in\mathbb N_{\ge t}$这样的话$u\mapsto\frac1u\ln^t(u)$正在上减少$[N,\infty)$那么,对于$n\ge n美元$,$$\sum_{\ell=N}^{N}\frac1\ell\ln^t(\ell)\ge\sum_}\ell=N}^{N}\int_{ell}^{\ell+1}\frac1u\ln^ t(u)\mathrm du=ln^{t+1}(N+1)-\ln^{t1}(N)$$
对于$d\in\mathbb N_{\ge 1}$、和$n\in\mathbb n_{\ge d}$,让$$\mathcal S_{n,d}:=\left\{left(S_1,\ldots,S_d\right)\subset[n]:S_1<\cdots<S_d\right\}$$和$$a_{n,d}=\sum_{left(s_1,\ldots,s_d\right)\in\mathcal s_{n,d}}\frac{d!}{\prod_{k=1}^d s_k}$$
引理: $$a{n+1,d+1}=a{n,d+1}+\frac{d+1}{n+1}a{n、d}$$
证明: \开始{align}a{n+1,d+1}&=sum{left(s_1,ldots,s{d+1}\right)在mathcal s_{n+1、d+1}\frac{(d+1)!}{prod_{k=1}^{d+1}\\&=\sum_{left(s_1,\ldots,s_{d+1}\right)在\mathcal s_{n+1,d+1},\,s_}d+1}=n+1}\frac{(d+1)!<n+1}\frac{(d+1)!}{\prod_{k=1}^{d+1}s_k}\\&=\sum_{left(s_1,\ldots,s_d\right)\in\mathcal s_{n,d}}\frac{(d+1)d!}{(n+1)\prod_{k=1}^d s_k}+\sum_{left\(s_1,\ldot,s_{d+1}\right\\&=\压裂{d+1}{n+1}a{n,d}+a{n、d+1}。\结束{对齐}
引理:对于$d\ge 1美元$,$\存在C_d>0$,$n>d美元$,$$a_{n,d}\ge C_d\ln^d(n)$$
证明:我们将使用归纳法$d=1$ $$a{n,1}=\sum{ell=1}^{n}\frac1\ell=H_n\ge\ln n$$假设这是真的$d美元$那么,订购$n>d+1$,\开始{align}a{n,d+1}&=a{d+1,d+1{+sum{k=d+1}^{n-1}左(a{k+1,d+1}-a{k,d+1)\\&=1+(d+1)\sum{k=d+1}^{n-1}\frac1{k+1}a{k,d}\\&\ge(d+1)C_d\sum_{k=d+1}^{n-1}\frac1\k+1}\ln^{d}(k)\\&\ge(d+1)\frac{C_d}{\alpha_d}\ln^{d+1}(n)。\结束{对齐}
这将完成导入$C_{d+1}=(d+1)\压裂{C_d}{\alpha_d}$.