Number of (1,0)-steps at levels 0,2,4,... in all peakless Motzkin paths of length n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =6a(5) =14a(6) =34a(7) =83a(8) =202a(9) =495a(10) =1224a(11) =3046a(12) =7616a(13) =19115a(14) =48130a(15) =121527a(16) =307602a(17) =780244a(18) =1982834a(19) =5047377a(20) =12867438a(21) =32847357a(22) =83952780a(23) =214806750a(24) =550170300a(25) =1410412561a(26) =3618785462a(27) =9292203549a(28) =23877482490a(29) =61397367692