a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 187) or the same sequence for the mesh pattern (12, 442).
A289592
a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 187) or the same sequence for the mesh pattern (12, 442).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =2a(4) =7a(5) =22a(6) =71a(7) =235a(8) =794a(9) =2728a(10) =9503a(11) =33488a(12) =119170a(13) =427652a(14) =1545878a(15) =5623753a(16) =20573960a(17) =75644700a(18) =279369615a(19) =1035917700a(20) =3855226650a(21) =14394913860a(22) =53911007250a(23) =202462899990a(24) =762283780284
External references
- oeis: A289592