➕ 等差数列计算器Arithmetic Sequence Calculator
输入首项、公差和项数，求第 n 项、前 n 项和，并列出数列各项。Find the nth term and the sum of the first n terms of an arithmetic sequence and list its terms.
使用说明与常见问题How-to & FAQ
「等差数列计算器」是什么？What is the Arithmetic Sequence Calculator tool?
输入首项、公差和项数，求第 n 项、前 n 项和，并列出数列各项。Find the nth term and the sum of the first n terms of an arithmetic sequence and list its terms.
如何使用「等差数列计算器」？How do I use the Arithmetic Sequence Calculator tool?
在「等差数列计算器」中，填写「首项 a₁」、「公差 d」、「项数 n」等参数，结果会随输入实时计算并显示在下方。In the Arithmetic Sequence Calculator: Fill in "First term a₁", "Common difference d", "Number of terms n"; results are recalculated instantly as you type.
计算精度如何？How precise are the results?
「等差数列计算器」使用 JavaScript 双精度浮点数（约 15–16 位有效数字）；极大或极小的数值可能存在精度误差。The Arithmetic Sequence Calculator uses double-precision floating point (about 15–16 significant digits); very large or very small values may lose precision.
「等差数列计算器」免费吗？需要注册吗？Is the Arithmetic Sequence Calculator free? Do I need an account?
「等差数列计算器」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Arithmetic Sequence Calculator is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.