A divisor analog of the Motzkin numbers A001006.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =7a(5) =12a(6) =29a(7) =56a(8) =134a(9) =283a(10) =672a(11) =1496a(12) =3568a(13) =8214a(14) =19678a(15) =46364a(16) =111766a(17) =267467a(18) =648941a(19) =1570540a(20) =3833777a(21) =9357181a(22) =22967808a(23) =56430230a(24) =139193762a(25) =343825265a(26) =851777363a(27) =2113382992a(28) =5255584309a(29) =13089273904