diff --git a/Algo/Séminaire/Exercices seminaire.md b/Algo/Séminaire/Exercices seminaire.md
index 3532aff..d2f4c6a 100644
--- a/Algo/Séminaire/Exercices seminaire.md	
+++ b/Algo/Séminaire/Exercices seminaire.md	
@@ -483,7 +483,7 @@ let is_prime n =
 			n = 2
 		else
 			let rec check d =
-				if d = n then
+				if d*d > n then
 					true
 				else if n mod d = 0 then
 					false
@@ -493,6 +493,22 @@ let is_prime n =
 					
 ```
 
+## 4.13 - Perfect
+```Ocaml
+let is_perfect n =
+	if n < 1 then
+		invalid_arg "is_perfect: undefinded for n < 1"
+	else 
+		let rec perfect d =
+			if n mod d = 0 then
+				if d*d > n then
+					true
+				else
+					perfect (d + 1)
+			else
+				 
+		in perfect d;;
+```
 ## Hanoi
 ```Ocaml
 (* displays moves: source -> destination *)