Squares of Motzkin numbers.

Terms

a(0) =1a(1) =1a(2) =4a(3) =16a(4) =81a(5) =441a(6) =2601a(7) =16129a(8) =104329a(9) =697225a(10) =4787344a(11) =33616804a(12) =240591121a(13) =1750167225a(14) =12912685956a(15) =96454967184a(16) =728405920089