Sum{T(i,n-i): i=0,1,...,n}, array T given by A047010.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =10a(5) =16a(6) =31a(7) =60a(8) =120a(9) =228a(10) =452a(11) =895a(12) =1790a(13) =3520a(14) =7018a(15) =13984a(16) =27968a(17) =55572a(18) =111004a(19) =221668a(20) =443336a(21) =884224a(22) =1767479a(23) =3532564a(24) =7065128a(25) =14112700a(26) =28218316a(27) =56418922a(28) =112837844a(29) =225544128