a(n) = A002865(2*n-1)+A002865(2*n).

Terms

a(0) =1a(1) =3a(2) =6a(3) =11a(4) =20a(5) =35a(6) =58a(7) =96a(8) =154a(9) =242a(10) =375a(11) =573a(12) =861a(13) =1282a(14) =1886a(15) =2745a(16) =3961a(17) =5667a(18) =8038a(19) =11323a(20) =15836a(21) =22001a(22) =30383a(23) =41715a(24) =56953a(25) =77363a(26) =104566a(27) =140668a(28) =188397a(29) =251247