Table of values for natural tetration:

y               E^^y               
-----------------------------------
-2              -00                
-1.993817117    -5                 
-1.983140903    -4                 
-1.95379385     -3                 
-1.9            -2.24186256        
-1.87177774     -2                 
-1.8            -1.57089786        
-1.7            -1.18320483        
-1.63635835     -1                 
-1.6            -0.90924165        
-1.5            -0.696024746       
-1.4            -0.52002168        
-1.3            -0.36870170        
-1.2            -0.23457848        
-1.1            -0.11279680        
-1              0                  
-0.9            0.106260403        
-0.8            0.20785847         
-0.7            0.30629553         
-0.6            0.40282959         
-0.5            0.30629553         
-0.4            0.59450765         
-0.3            0.69163168         
-0.2            0.79090415         
-0.1            0.893332165        
-0.01           0.989109262        
-0.001          0.9989085038       
0               1                  
0.001           1.0010920390       
0.01            1.010945035        
0.1             1.112111436        
0.2             1.23103893         
0.3             1.35838370         
0.4             1.49605193         
0.40274679      1.5                
0.5             1.646354229        
0.6             1.81213852         
0.7             1.99697131         
0.70154560      2                  
0.8             2.20538954         
0.9             2.44325744         
0.92190054      2.5                
1               E                  
1.08824913      3                  
1.1             3.04077201         
1.12805960      Pi                 
1.2             3.4247858          
1.3             3.8899009          
1.32094578      4                  
1.4             4.4640299          
1.476292652     5                  
1.5             5.18803093         
1.588256745     6                  
1.6             6.1235287          
GoldenRatio     6.3214336          
1.67350519      7                  
1.7             7.3667108          
1.74108261      8                  
1.79631368      9                  
1.8             9.073785           
1.84254179      10                 
1.88197718      11                 
1.9             11.5104744         
1.916143363     12                 
1.946127230     13                 
1.972726899     14                 
1.996542905     15                 
2               E^E                
2.018036687     16                 
2.037569295     17                 
2.055427751     18                 
2.071843439     19                 
2.08700521      20                 
2.1             20.9213886         
2.10106895      21                 
2.11416459      22                 
2.12640140      23                 
2.13787206      24                 
2.14865577      25                 
2.19436316      30                 
2.2             30.716064          
2.23013908      35                 
2.25922067      40                 
2.28352820      45                 
2.3             48.906043          
2.30428383      50                 
2.4             86.83675           
2.421477413     100                
2.5             179.115515         
2.5132672975    200                
2.55842860      300                
2.58743083      400                
2.6             456.4726           
2.60841520      500                
2.66648471      1000               
2.7             1582.4203          
2.71583365      2000               
E               2075.9682          
2.8             8723.584           
2.8066977       10000              
2.9             99755.19           
3               E^E^E              
3.1             1.219112e9         
Pi              3.714981e10        
3.2             2.18684e13         
3.3             1.736299e21        
3.4             5.16085e37         
3.5             6.15006e77         
3.5003315224    1e78               
3.501885978     1e79               
3.503414837     1e80               
3.504918847     1e81               
3.529577845     Googol             
3.6             1.7520e198         
3.7             1.723e687          
3.8             4.02e3788          
3.9             1.35e43323         
4               E^E^E^E            
4.1             1.087891e529453652 
4.529987400     GoogolPlex         
5               Overflow