a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 170).

A289452

a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 170).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =9a(6) =16a(7) =48a(8) =102a(9) =289a(10) =693a(11) =1902a(12) =4883a(13) =13296a(14) =35415a(15) =96778a(16) =263217a(17) =724590a(18) =1996899a(19) =5539806a(20) =15410025a(21) =43051125a(22) =120615282a(23) =339009948a(24) =955322052a(25) =2699027073a(26) =7642788987a(27) =21688832038a(28) =61670656557a(29) =175682146971

External references