a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 381) or the same sequence for the mesh pattern (12, 471).

A289612

a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 381) or the same sequence for the mesh pattern (12, 471).

Terms

    a(0) =1a(1) =1a(2) =3a(3) =10a(4) =34a(5) =116a(6) =397a(7) =1366a(8) =4734a(9) =16540a(10) =58274a(11) =206988a(12) =740852a(13) =2670344a(14) =9686653a(15) =35341286a(16) =129612022a(17) =477573164a(18) =1767132118a(19) =6563858276a(20) =24465742732a(21) =91481515064a(22) =343057516498

External references