a(0) = 1; for n > 0, a(n) = binomial(n, floor(n/2)) + binomial(n-1, floor(n/2)).

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =9a(5) =16a(6) =30a(7) =55a(8) =105a(9) =196a(10) =378a(11) =714a(12) =1386a(13) =2640a(14) =5148a(15) =9867a(16) =19305a(17) =37180a(18) =72930a(19) =140998a(20) =277134a(21) =537472a(22) =1058148a(23) =2057510a(24) =4056234a(25) =7904456a(26) =15600900a(27) =30458900a(28) =60174900a(29) =117675360