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

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =2a(6) =2a(7) =2a(8) =4a(9) =6a(10) =6a(11) =6a(12) =9a(13) =12a(14) =12a(15) =12a(16) =16a(17) =20a(18) =20a(19) =20a(20) =25a(21) =30a(22) =30a(23) =30a(24) =36a(25) =42a(26) =42a(27) =42a(28) =49a(29) =56