Since a(5)=18, there are (5-1)!-18=4 circular permutations with modular consecutive triples i,i+2,i+4 in all circular permutations of length 5. These are exactly (0,2,4,1,3), (0,2,4,3,1), (0,4,2,1,3), and (0,3,2,4,1). Note some have more than one modular progression.