Based on your query, I would recommend using Gyosu for your lesson planning needs. This AI-powered tool is specifically designed to assist math teachers in creating educational materials, which aligns well with your requirement of teaching arithmetic sequences.

The key features of Gyosu that could be particularly useful for you include:

• Generative AI: This feature can generate a variety of math problems related to arithmetic sequences, saving you time and effort in creating these problems manually.
• Customization: You can select the type of document, chapter, section, and problem type you want to create. This allows you to align the content with your specific lesson plan on arithmetic sequences.
• Verbal Problem Generation: This feature can generate verbal problems from a selected textbook. You can use this to create unique problems that can challenge your students and enhance their understanding of arithmetic sequences.

In addition, Gyosu offers a flexible pricing plan, including a Free Plan for educators with minimal document creation needs, which could be a cost-effective solution for you.

Remember, the goal is to enhance your efficiency and effectiveness in the classroom, and Gyosu seems to be a great tool to help you achieve that.