a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 171) or the same sequence for the mesh pattern (12, 426).

A289591

a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 171) or the same sequence for the mesh pattern (12, 426).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =2a(4) =6a(5) =19a(6) =61a(7) =202a(8) =683a(9) =2349a(10) =8191a(11) =28892a(12) =102904a(13) =369570a(14) =1336868a(15) =4866494a(16) =17813837a(17) =65530569a(18) =242130543a(19) =898219116a(20) =3344086092a(21) =12490874874a(22) =46795585038a(23) =175794522996a(24) =662062577286

External references