Number of permutations of [n] avoiding {1324, 2143, 3412}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =71a(6) =222a(7) =648a(8) =1797a(9) =4807a(10) =12548a(11) =32236a(12) =82009a(13) =207529a(14) =524060a(15) =1323540a(16) =3348087a(17) =8491157a(18) =21600888a(19) =55131630a(20) =141172311a(21) =362617861a(22) =934098062a(23) =2412413026a(24) =6244420411a(25) =16195018711a(26) =42072199862a(27) =109451155098a(28) =285073305417a(29) =743218623827