Number of Motzkin meanders of length n with an even number of peaks.

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =22a(5) =56a(6) =148a(7) =402a(8) =1112a(9) =3118a(10) =8832a(11) =25205a(12) =72342a(13) =208560a(14) =603404a(15) =1750785a(16) =5092046a(17) =14839710a(18) =43321976a(19) =126661355a(20) =370813762a(21) =1086877792a(22) =3189091724a(23) =9366371000a(24) =27533212140a(25) =81001276874a(26) =238478223648a(27) =702592110803