Number of permutations of [n] avoiding {1324, 3421, 3241}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =75a(6) =259a(7) =852a(8) =2669a(9) =7997a(10) =23043a(11) =64190a(12) =173677a(13) =458255a(14) =1183139a(15) =2997544a(16) =7470237a(17) =18349057a(18) =44497747a(19) =106691218a(20) =253229501a(21) =595589331a(22) =1389361107a(23) =3217028796a(24) =7398749581a(25) =16911430725a(26) =38436598499a(27) =86905975142a(28) =195555225549a(29) =438086659607