Presidential Regnal Numbers

One aspect (well, there are others) in which American leaders have been sorely lacking is that of regnal numbers. (Yes, perhaps they are more associated with royalty, but as the government continues to centralize and accrue ever more power in the executive branch, we'll soon be wondering, why not?) So, here's a list:

1. George I
   
2. John I
   
3. Thomas
   
4. James I
   
5. James II
   
6. John II
   
7. Andrew I
   
8. Martin
   
9. William I
   
10. John III
    
11. James III
    
12. Zachary
    
13. Millard
    
14. Franklin I
    
15. James IV
    
16. Abraham
    
17. Andrew II
    
18. Ulysses
    
19. Rutherford
    
20. James V
    
21. Chester
    
22. Grover
    
23. Benjamin
    
24. Grover [restored]
    
25. William II
    
26. Theodore
    
27. William III
    
28. Woodrow
    
29. Warren
    
30. Calvin
    
31. Herbert
    
32. Franklin II
    
33. Harry
    
34. Dwight
    
35. John IV
    
36. Lyndon
    
37. Richard
    
38. Gerald
    
39. James VI
    
40. Ronald
    
41. George II
    
42. William IV
    
43. George III
    
44. Barack

Statistics:

• There have been six Jameses, four Johns, four Williams, three Georges, two Andrews, and two Franklins. All the other presidents—twenty-two of them—are uniquely named.
• The greatest gap between two presidents with the same name is 192 years, between George I (Washington) and George II (Bush). The only president to follow another with the same name was James II (Monroe), coming directly after James I (Madison).
• Only two presidents have been the son of a president, and both had their father's name: John II (Adams) and George III. One president, Benjamin, was the grandson of another, William I. Most presidents are more distantly related to other presidents, though.
• Fourteen presidential names are those of saints; five are those of British monarchs. Seven were originally surnames; two were place names. At least three (Millard, Grover, and Woodrow) sound frankly bizarre today.
  
• Fourteen are ultimately of Germanic origin; five are Hebrew; three are Greek, three Latin, one Aramaic, one French, and one Arabic (guess which?).