a(n) = Sum_{d|n, d <= 4} d^2 + 4*Sum_{d|n, d>4} d.

Terms

a(0) =1a(1) =5a(2) =10a(3) =21a(4) =21a(5) =38a(6) =29a(7) =53a(8) =46a(9) =65a(10) =45a(11) =102a(12) =53a(13) =89a(14) =90a(15) =117a(16) =69a(17) =146a(18) =77a(19) =161a(20) =122a(21) =137a(22) =93a(23) =230a(24) =121a(25) =161a(26) =154a(27) =217a(28) =117a(29) =278