Number of permutations of length n which avoid the patterns 321, 1342, 3124.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =22a(6) =37a(7) =60a(8) =96a(9) =153a(10) =244a(11) =390a(12) =625a(13) =1004a(14) =1616a(15) =2605a(16) =4204a(17) =6790a(18) =10973a(19) =17740a(20) =28688a(21) =46401a(22) =75060a(23) =121430a(24) =196457a(25) =317852a(26) =514272a(27) =832085a(28) =1346316a(29) =2178358