a(1) = 1, a(m+1) = 2*Sum_{k=1..floor((m+1)/2)} a(k).

Terms

a(0) =1a(1) =2a(2) =2a(3) =6a(4) =6a(5) =10a(6) =10a(7) =22a(8) =22a(9) =34a(10) =34a(11) =54a(12) =54a(13) =74a(14) =74a(15) =118a(16) =118a(17) =162a(18) =162a(19) =230a(20) =230a(21) =298a(22) =298a(23) =406a(24) =406a(25) =514a(26) =514a(27) =662a(28) =662a(29) =810