Deriving a formula for half integer factorials.

Feynman Academy course: https://feynman-academy-course.vercel.app/#/join Chapters 1 and 2 are free. Chapter 3 and beyond start with a 7-day trial, then $10/month unless canceled. Subscribe: https://www.youtube.com/channel/UCepKxh_j0SH2cw0nbY9FwZQ?sub_confirmation=1 Course path (Jan 18, 2026 and newer) Lesson 25 of 32 Start here: https://youtu.be/8xq0RW1VurI Previous lesson: https://youtu.be/AttqfdQp7js Next lesson: https://youtu.be/XLBEQsW4Ko4 About this lesson: Ever wondered how to take the factorial of 2.5? In this interactive Feynman Lab, we derive the exact formula for half-integer Gamma functions. We'll use the Gamma recurrence relation and the famous Gaussian integral to uncover a beautiful closed-form result.