a(n) = floor(n/4)*ceiling((n+3)/4).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =2a(6) =3a(7) =3a(8) =6a(9) =6a(10) =8a(11) =8a(12) =12a(13) =12a(14) =15a(15) =15a(16) =20a(17) =20a(18) =24a(19) =24a(20) =30a(21) =30a(22) =35a(23) =35a(24) =42a(25) =42a(26) =48a(27) =48a(28) =56a(29) =56