a(n) = floor(n/4)*floor((n+1)/4)*floor((n+2)/4).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =1a(6) =2a(7) =4a(8) =8a(9) =8a(10) =12a(11) =18a(12) =27a(13) =27a(14) =36a(15) =48a(16) =64a(17) =64a(18) =80a(19) =100a(20) =125a(21) =125a(22) =150a(23) =180a(24) =216a(25) =216a(26) =252a(27) =294a(28) =343a(29) =343