a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 273).

A289603

a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 273).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =22a(6) =91a(7) =349a(8) =1277a(9) =4570a(10) =16235a(11) =57698a(12) =205883a(13) =738704a(14) =2666127a(15) =9678317a(16) =35324733a(17) =129579058a(18) =477507403a(19) =1767000790a(20) =6563595843a(21) =24465218120a(22) =91480466127a(23) =343055418946

External references