a(n) = A186434(n)/4.

Terms

a(0) =0a(1) =1a(2) =9a(3) =37a(4) =111a(5) =266a(6) =550a(7) =1006a(8) =1744a(9) =2821a(10) =4349a(11) =6405a(12) =9203a(13) =12804a(14) =17418a(15) =23164a(16) =30348a(17) =39023a(18) =49591a(19) =62073a(20) =76997a(21) =94454a(22) =114768a(23) =138054a(24) =165176a(25) =196019a(26) =231085a(27) =270557a(28) =315283a(29) =365102