diff --git a/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
index 0bcf279..5635770 100644
--- a/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
+++ b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
@@ -11,7 +11,7 @@ public class EnumerableExtensionsTest
         var actual = data.Combinations(2).ToArray();
 
         Assert.Contains([1, 2], actual);
-        Assert.Equal(1, actual.Length);
+        Assert.Single(actual);
     }
     
     [Fact]
@@ -35,7 +35,37 @@ public class EnumerableExtensionsTest
         var actual = data.Combinations(3).ToArray();
 
         Assert.Contains([1, 2, 3], actual);
-        Assert.Equal(1, actual.Length);
+        Assert.Single(actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_12_2_equals_11_12_22()
+    {
+        int[] data = [1, 2];
+
+        var actual = data.CombinationsWithRepeats(2).ToArray();
+        
+        Assert.Equal([[1, 1], [1, 2], [2, 2]], actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_123_2_equals_11_12_13_22_23_33()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.CombinationsWithRepeats(2).ToArray();
+
+        Assert.Equal([[1, 1], [1, 2], [1, 3], [2, 2], [2, 3], [3, 3]], actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_123_3_equals_many()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.CombinationsWithRepeats(3).ToArray();
+        
+        Assert.Equal([[1, 1, 1], [1, 1, 2], [1, 1, 3], [1, 2, 2], [1, 2, 3], [1, 3, 3], [2, 2, 2], [2, 2, 3], [2, 3, 3], [3, 3, 3]], actual);
     }
     
     [Fact]
diff --git a/AdventOfCode.Extensions/EnumerableExtensions.cs b/AdventOfCode.Extensions/EnumerableExtensions.cs
index 3be3644..1994e6d 100644
--- a/AdventOfCode.Extensions/EnumerableExtensions.cs
+++ b/AdventOfCode.Extensions/EnumerableExtensions.cs
@@ -12,14 +12,15 @@ public static class EnumerableExtensions
         var poolLength = pool.Length;
         if (count > poolLength)
             yield break;
-        var indices = Enumerable.Range(0, count).ToArray();
+        int[] indices = [..Enumerable.Range(0, count)];
         yield return GetCombination(indices, pool);
         while (true)
         {
             var idx = count - 1;
             for(;idx >= 0; --idx)
             {
-                var isIndexBelowMax = indices[idx] != idx + poolLength - count;
+                var maxPossibleIndex = idx + poolLength - count;
+                var isIndexBelowMax = indices[idx] != maxPossibleIndex;
                 if (isIndexBelowMax) 
                     break;
             }
@@ -27,7 +28,7 @@ public static class EnumerableExtensions
                 yield break;
             
             indices[idx] += 1;
-            for (var j = idx + 1; j < count; j++)
+            for (var j = idx + 1; j < indices.Length; j++)
             {
                 indices[j] = indices[j - 1] + 1;
             }
@@ -36,6 +37,37 @@ public static class EnumerableExtensions
         }
     }
     
+    public static IEnumerable<TValue[]> CombinationsWithRepeats<TValue>(this IEnumerable<TValue> values, int count)
+    {
+        var pool = values.ToArray();
+        var poolLength = pool.Length;
+        if (count > poolLength)
+            yield break;
+        int[] indices = [..Enumerable.Repeat(0, count)];
+        yield return GetCombination(indices, pool);
+        while (true)
+        {
+            var idx = count - 1;
+            for(;idx >= 0; --idx)
+            {
+                var maxPossibleIndex = poolLength - 1;
+                var isIndexBelowMax = indices[idx] != maxPossibleIndex;
+                if (isIndexBelowMax) 
+                    break;
+            }
+            if(idx < 0)
+                yield break;
+            
+            var num = indices[idx];
+            for (var j = idx; j < indices.Length; j++)
+            {
+                indices[j] = num + 1;
+            }
+
+            yield return GetCombination(indices, pool);
+        }
+    }
+    
     public static IEnumerable<TValue[]> Permutations<TValue>(this IEnumerable<TValue> values, int count)
     {
         var pool = values.ToArray();