DOC: fixup formula for exponentially weighted mean with input vector …
diff --git a/doc/source/user_guide/window.rst b/doc/source/user_guide/window.rst
index ad710b865acea..4a560f6b23932 100644
--- a/doc/source/user_guide/window.rst
+++ b/doc/source/user_guide/window.rst
@@ -581,7 +581,7 @@ The following formula is used to compute exponentially weighted mean with an inp
 
 .. math::
 
-    y_t = \frac{\sum_{i=0}^t 0.5^\frac{t_{t} - t_{i}}{\lambda} x_{t-i}}{0.5^\frac{t_{t} - t_{i}}{\lambda}},
+    y_t = \frac{\sum_{i=0}^t 0.5^\frac{t_{t} - t_{i}}{\lambda} x_{t-i}}{\sum_{i=0}^t 0.5^\frac{t_{t} - t_{i}}{\lambda}},
 
 
 ExponentialMovingWindow also has an ``ignore_na`` argument, which determines how

…of times? #40327

- [x] closes #40327 
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry
