Sum of all n-digit Motzkin numbers.

Terms

a(0) =17a(1) =72a(2) =1285a(3) =7986a(4) =57346a(5) =1277673a(6) =8893161a(7) =69051303a(8) =543310782a(9) =13365890713a(10) =98677591278a(11) =801766063038