Number of permutations of [n] avoiding {1324, 2413, 2431}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =77a(6) =285a(7) =1053a(8) =3875a(9) =14212a(10) =52021a(11) =190301a(12) =696532a(13) =2553047a(14) =9377034a(15) =34525630a(16) =127466481a(17) =471935813a(18) =1752332838a(19) =6525032251a(20) =24363932865a(21) =91214649344a(22) =342358204917