Number of permutations of length n which avoid the patterns 2314, 4132, 4321.

Terms

a(0) =1a(1) =2a(2) =6a(3) =21a(4) =72a(5) =228a(6) =678a(7) =1929a(8) =5307a(9) =14203a(10) =37133a(11) =95179a(12) =239942a(13) =596587a(14) =1466529a(15) =3571386a(16) =8630575a(17) =20725008a(18) =49509197a(19) =117762285a(20) =279109649a(21) =659555800a(22) =1554707004a(23) =3657127140a(24) =8587557316a(25) =20135214390a(26) =47151860695a(27) =110301150860