Number of permutations of length n which avoid the patterns 2143, 2341, 3214.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =72a(5) =237a(6) =761a(7) =2415a(8) =7626a(9) =24034a(10) =75689a(11) =238298a(12) =750179a(13) =2361533a(14) =7433917a(15) =23401274a(16) =73664906a(17) =231889749a(18) =729965584a(19) =2297858029a(20) =7233425149a(21) =22770092131a(22) =71677951146a(23) =225634953382a(24) =710276052265