Number of Motzkin meanders of length n with an even number of humps and without peaks.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =32a(6) =65a(7) =136a(8) =298a(9) =691a(10) =1694a(11) =4340a(12) =11433a(13) =30510a(14) =81592a(15) =217238a(16) =573970a(17) =1503296a(18) =3904181a(19) =10065079a(20) =25796324a(21) =65837541a(22) =167602092a(23) =426213784a(24) =1084095329a(25) =2760717190a(26) =7043305930a(27) =18008810836a(28) =46151503544a(29) =118529776510