Number of cyclic permutations of length n avoiding the pattern 231 (equivalently, 312).

A309506

Number of cyclic permutations of length n avoiding the pattern 231 (equivalently, 312).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =5a(6) =12a(7) =30a(8) =86a(9) =253a(10) =748a(11) =2274a(12) =7152a(13) =22890a(14) =74189a(15) =243342a(16) =808599a(17) =2716549a(18) =9213420a(19) =31498358a(20) =108483093a(21) =376145636a(22) =1312463081a(23) =4605569378a(24) =16245866825

External references