# double ones from Boolos, Burgess & Jeffrey

(0,1,1,1,l) 
(1, , ,2,l) 
(1,1,1,2,l) 
(2, ,1,3,l) 
(2,1,1,3,l) 
(3, ,1,4,r) 
(3,1,1,4,r) 
(4,1,1,4,r) 
(4, , ,5,r) 
(5,1,1,5,r) 
(5, , ,6,l) 
(6,1, ,7,l) 
(6, , ,7,l) 
(7, , ,8,l) 
(7,1,1,9,l) 
(9,1,1,9,l) 
(9, , ,10,l) 
(10,1,1,10,l) 
(10, , ,1,r) 
(8,1,1,8,l) 
(8, , ,11,r)