a(n) = floor(n/2)^3 - floor(n/3)^3.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =7a(5) =7a(6) =19a(7) =19a(8) =56a(9) =37a(10) =98a(11) =98a(12) =152a(13) =152a(14) =279a(15) =218a(16) =387a(17) =387a(18) =513a(19) =513a(20) =784a(21) =657a(22) =988a(23) =988a(24) =1216a(25) =1216a(26) =1685a(27) =1468a(28) =2015a(29) =2015