CLCS

Sharpsign O

#Orational reads rational in octal (radix 8). For example,

 #o37/15 ≡ 31/13
 #o777 ≡ 511
 #o105 ≡ 69 ;105_8

The consequences are undefined if the token immediately following the #O does not have the syntax of an octal (i.e., radix 8) rational.