a(n) = Sum_{d|n} d*sigma(n/d)*sigma(d).

Terms

a(0) =1a(1) =9a(2) =16a(3) =53a(4) =36a(5) =144a(6) =64a(7) =261a(8) =178a(9) =324a(10) =144a(11) =848a(12) =196a(13) =576a(14) =576a(15) =1173a(16) =324a(17) =1602a(18) =400a(19) =1908a(20) =1024a(21) =1296a(22) =576a(23) =4176a(24) =986a(25) =1764a(26) =1744a(27) =3392a(28) =900a(29) =5184