a(n) = Sum_{d|n, d==0 mod 3} d^2.

Terms

a(0) =0a(1) =0a(2) =9a(3) =0a(4) =0a(5) =45a(6) =0a(7) =0a(8) =90a(9) =0a(10) =0a(11) =189a(12) =0a(13) =0a(14) =234a(15) =0a(16) =0a(17) =450a(18) =0a(19) =0a(20) =450a(21) =0a(22) =0a(23) =765a(24) =0a(25) =0a(26) =819a(27) =0a(28) =0a(29) =1170