Number of meanders of length n with Motzkin-steps avoiding the consecutive steps UU.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =20a(5) =46a(6) =107a(7) =252a(8) =599a(9) =1435a(10) =3460a(11) =8389a(12) =20437a(13) =49996a(14) =122758a(15) =302401a(16) =747114a(17) =1850696a(18) =4595370a(19) =11435380a(20) =28513149a(21) =71225270a(22) =178219696a(23) =446637759a(24) =1120946389a(25) =2817089354a(26) =7088656546a(27) =17858286741a(28) =45039810918a(29) =113711798916