diff --git a/rpn/math/rpnLexicographic.py b/rpn/math/rpnLexicographic.py
index b7528c3..51db125 100644
--- a/rpn/math/rpnLexicographic.py
+++ b/rpn/math/rpnLexicographic.py
@@ -275,7 +275,7 @@ def combineDigits( n ):
     listResult = False
 
     for i in n:
-        if isinstance( i, ( list, RPNGenerator ) ) and result == 0:
+        if isinstance( i, ( list, types.GeneratorType, RPNGenerator ) ) and result == 0:
             listResult = True
             result = combineDigits( i )
         elif listResult:
diff --git a/rpn/math/rpnNumberTheory.py b/rpn/math/rpnNumberTheory.py
index 0839d0e..38cc82d 100644
--- a/rpn/math/rpnNumberTheory.py
+++ b/rpn/math/rpnNumberTheory.py
@@ -2409,7 +2409,8 @@ def getNthZetaZeroOperator( n ):
     48:  57885161,
     49:  74207281,
     50:  77232917,
-    51:  82589933
+    51:  82589933,
+    52:  136279841
 }
 
 
diff --git a/rpn/special/rpnList.py b/rpn/special/rpnList.py
index 742805b..5fa8300 100644
--- a/rpn/special/rpnList.py
+++ b/rpn/special/rpnList.py
@@ -920,13 +920,16 @@ def reduceListOperator( n ):
 #******************************************************************************
 
 def calculateGeometricMean( args ):
-    if isinstance( args[ 0 ], ( list, types.GeneratorType ) ):
-        return [ calculateGeometricMean( list( arg ) ) for arg in args ]
+    if not isinstance( args, types.GeneratorType ):
+        if isinstance( args[ 0 ], ( list, types.GeneratorType ) ):
+            return [ calculateGeometricMean( arg ) for arg in args ]
 
     result = mpmathify( 1 )
     count = 0
 
     for arg in args:
+        print( 'arg', arg, type( arg ) )
+        
         result = fmul( result, arg )
         count += 1