a(n) = A028317(n)/2.

Terms

a(0) =3a(1) =3a(2) =6a(3) =4a(4) =4a(5) =19a(6) =5a(7) =18a(8) =18a(9) =5a(10) =23a(11) =65a(12) =23a(13) =6a(14) =6a(15) =102a(16) =189a(17) =231a(18) =189a(19) =102a(20) =7a(21) =41a(22) =291a(23) =420a(24) =420a(25) =291a(26) =41a(27) =7a(28) =48a(29) =711