Number of permutations of length n that avoid the patterns 321, 1342, 4123.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =12a(5) =24a(6) =46a(7) =87a(8) =162a(9) =300a(10) =554a(11) =1021a(12) =1880a(13) =3460a(14) =6366a(15) =11711a(16) =21542a(17) =39624a(18) =72882a(19) =134053a(20) =246564a(21) =453504a(22) =834126a(23) =1534199a(24) =2821834a(25) =5190164a(26) =9546202a(27) =17558205a(28) =32294576a(29) =59398988