MathWorld - Eric Weisstein
http://mathworld.wolfram.com/BaseNumber.html

Base Name
2 binary
3 ternary
4 quaternary
5 quinary
6 senary
7 septenary
8 octal
9 nonary
10 decimal
11 undenary
12 duodecimal
16 hexadecimal
20 vigesimal
60 sexagesimal