Number of Motzkin paths of length n with no level steps at odd level.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =6a(5) =11a(6) =23a(7) =47a(8) =102a(9) =221a(10) =493a(11) =1105a(12) =2516a(13) =5763a(14) =13328a(15) =30995a(16) =72556a(17) =170655a(18) =403351a(19) =957135a(20) =2279948a(21) =5449013a(22) =13063596a(23) =31406517a(24) =75701508a(25) =182902337a(26) =442885683a(27) =1074604289a(28) =2612341856a(29) =6361782007