本文推廣了多重小數(shù)部分和的漸近式與 Ovidiu Furdui 積分問題一文中的結果。
最近,王永強先生推廣 $2$ 重和式的結果,然后我將其推廣到 $k$ 重和式。具體文章將繼續(xù)投稿給大學數(shù)學雜志。
|
對于正整數(shù) $k\geqslant 3$, 正整數(shù) $a_1,\dotsc, a_k \in \mathbb{N}_{+}$ 互素 $(a_1,\dotsc,a_k)=1$. \begin{align*} & \quad \sum_{n_1 \leqslant x} \dotsc \sum_{n_{k} \leqslant x} \left\{ \frac{x}{a_1n_1+\dotsb+a_kn_k} \right\} \\ & = \Bigg( \frac{1}{(k-1)! a_1 \dotsm a_k} \bigg( \sum_{1\leqslant i \leqslant k} (-1)^{k+1} a_{i}^{k-1} \log a_{i} + \sum_{1\leqslant i_1 < i_2 \leqslant k} (-1)^{k+2} (a_{i_{1}}+a_{i_{2}})^{k-1} \log(a_{i_1}+a_{i_2}) \\ & \quad + \sum_{1\leqslant i_1 < i_2 <i_3 \leqslant k} (-1)^{k+3} (a_{i_{1}}+a_{i_{2}}+a_{i_{3}})^{k-1} \log(a_{i_1}+a_{i_2}+a_{i_3}) + \dotsb \\ &\quad + (a_1+\dotsb+a_k)^{k-1} \log(a_1+\dotsb +a_k) \bigg) - \frac{\zeta(k)}{k! a_1\dotsm a_k} \Bigg)x^{k} + O(x^{k-1}) \end{align*}
|
對應的我們有小數(shù)部分積分
|
對于正整數(shù) $k\geqslant 2$, 正整數(shù) $a_1,\dotsc, a_k \in \mathbb{N}_{+}$ 互素 $(a_1,\dotsc,a_k)=1$. \begin{align*} &\quad \int_{0}^{1} \dotsi \int_{0}^{1} \left\{ \frac{1}{a_1t_1+\dotsb+a_kt_k} \right\} \, \mathrmw0obha2h00t_1 \dotsm \mathrmw0obha2h00t_k \\ & = \frac{1}{(k-1)! a_1 \dotsm a_k} \bigg( \sum_{1\leqslant i \leqslant k} (-1)^{k+1} a_{i}^{k-1} \log a_{i} + \sum_{1\leqslant i_1 < i_2 \leqslant k} (-1)^{k+2} (a_{i_{1}}+a_{i_{2}})^{k-1} \log(a_{i_1}+a_{i_2}) \\ & \quad + \sum_{1\leqslant i_1 < i_2 <i_3 \leqslant k} (-1)^{k+3} (a_{i_{1}}+a_{i_{2}}+a_{i_{3}})^{k-1} \log(a_{i_1}+a_{i_2}+a_{i_3}) + \dotsb \\ &\quad + (a_1+\dotsb+a_k)^{k-1} \log(a_1+\dotsb +a_k) \bigg) - \frac{\zeta(k)}{k! a_1\dotsm a_k} \end{align*} 當 $k=1$ 時, 實數(shù) $a_1 \geqslant 1$ \begin{equation*} \int_{0}^{1} \left\{ \frac{1}{a_{1}t_{1}} \right\} \, \mathrmw0obha2h00t_1 = \frac{1- \gamma +\log a_{1}}{a_{1}}. \end{equation*}
|