Number of Motzkin excursions of length n with an odd number of humps and without peaks.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =7a(6) =15a(7) =31a(8) =63a(9) =128a(10) =262a(11) =545a(12) =1161a(13) =2547a(14) =5767a(15) =13456a(16) =32202a(17) =78544a(18) =194016a(19) =482726a(20) =1204874a(21) =3008782a(22) =7505420a(23) =18689551a(24) =46454971a(25) =115296751a(26) =285886839a(27) =708673484a(28) =1757339598a(29) =4361894604