Number of Motzkin n-paths avoiding odd-numbered steps that are up steps.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =6a(6) =10a(7) =21a(8) =37a(9) =80a(10) =146a(11) =322a(12) =602a(13) =1347a(14) =2563a(15) =5798a(16) =11181a(17) =25512a(18) =49720a(19) =114236a(20) =224540a(21) =518848a(22) =1027038a(23) =2384538a(24) =4748042a(25) =11068567a(26) =22150519a(27) =51817118a(28) =104146733a(29) =244370806