a(1) = 2, a(2) = 2, a(3) = 1, a(n) = a(n-3) + floor(a(n-2)/2) for n >= 4.

Terms

a(0) =2a(1) =2a(2) =1a(3) =3a(4) =2a(5) =2a(6) =4a(7) =3a(8) =4a(9) =5a(10) =5a(11) =6a(12) =7a(13) =8a(14) =9a(15) =11a(16) =12a(17) =14a(18) =17a(19) =19a(20) =22a(21) =26a(22) =30a(23) =35a(24) =41a(25) =47a(26) =55a(27) =64a(28) =74a(29) =87