ANSI Common Lisp 2 Syntax 2.4 Standard Macro Characters 2.4.8 Sharpsign
18.104.22.168 Sharpsign O
#Orational reads rational in octal (radix 8). For example,
#o37/15 ==31/13 #o777 ==511 #o105 ==69 ;1058
The consequences are undefined if the token immediately following the #O does not have the syntax of an octal (i.e., radix 8) rational.