Number of Motzkin n-paths avoiding even-numbered steps that are flat steps.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =7a(6) =11a(7) =28a(8) =46a(9) =122a(10) =207a(11) =562a(12) =977a(13) =2693a(14) =4769a(15) =13288a(16) =23872a(17) =67064a(18) =121862a(19) =344588a(20) =631958a(21) =1796518a(22) =3319923a(23) =9479780a(24) =17630692a(25) =50532640a(26) =94493713a(27) =271710662a(28) =510468519a(29) =1471935235