Number of ascent sequences avoiding the pattern 120.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =14a(5) =42a(6) =133a(7) =442a(8) =1535a(9) =5546a(10) =20754a(11) =80113a(12) =317875a(13) =1292648a(14) =5374073a(15) =22794182a(16) =98462847a(17) =432498659a(18) =1929221610a(19) =8728815103a(20) =40017844229a(21) =185727603829a(22) =871897549029