diff --git a/the on-line encyclopedia of integer sequences.md b/the on-line encyclopedia of integer sequences.md
index a08cff647..c8758b3d2 100644
--- a/the on-line encyclopedia of integer sequences.md	
+++ b/the on-line encyclopedia of integer sequences.md	
@@ -3,3 +3,4 @@
   - e.g.
     - [[mersenne numbers]] https://oeis.org/A000225
     - [[mersenne primes]] https://oeis.org/A001348
+    - [[hex numbers]] https://oeis.org/search?q=1%2C7%2C19%2C37%2C61%2C91