Number of permutations of length n which avoid the patterns 231, 1423, 3214.

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =26a(5) =52a(6) =98a(7) =177a(8) =310a(9) =531a(10) =895a(11) =1491a(12) =2463a(13) =4044a(14) =6611a(15) =10774a(16) =17520a(17) =28446a(18) =46136a(19) =74771a(20) =121116a(21) =196117a(22) =317485a(23) =513877a(24) =831661a(25) =1345862a(26) =2177873a(27) =3524112a(28) =5702390a(29) =9226936