a(n) = ceiling(a(n-1)/2) + a(n-2) with a(0)=0 and a(1)=1.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =2a(5) =3a(6) =4a(7) =5a(8) =7a(9) =9a(10) =12a(11) =15a(12) =20a(13) =25a(14) =33a(15) =42a(16) =54a(17) =69a(18) =89a(19) =114a(20) =146a(21) =187a(22) =240a(23) =307a(24) =394a(25) =504a(26) =646a(27) =827a(28) =1060a(29) =1357