Number of permutations of [n] avoiding {4231, 2143, 1234}.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =21a(5) =69a(6) =190a(7) =446a(8) =927a(9) =1745a(10) =3036a(11) =4960a(12) =7701a(13) =11467a(14) =16490a(15) =23026a(16) =31355a(17) =41781a(18) =54632a(19) =70260a(20) =89041a(21) =111375a(22) =137686a(23) =168422a(24) =204055a(25) =245081a(26) =292020a(27) =345416a(28) =405837a(29) =473875