Related to number of mesh patterns of length 2 that avoid the pattern 231 or 321. For details see the comment section.

A289450

Related to number of mesh patterns of length 2 that avoid the pattern 231 or 321. For details see the comment section.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =3a(4) =10a(5) =33a(6) =109a(7) =364a(8) =1233a(9) =4236a(10) =14740a(11) =51868a(12) =184298a(13) =660400a(14) =2383928a(15) =8661433a(16) =31649818a(17) =116242093a(18) =428878333a(19) =1588858033a(20) =5908076563a(21) =22042959973a(22) =82495136173a(23) =309605919163

External references