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

Terms

a(0) =1a(1) =9a(2) =16a(3) =89a(4) =36a(5) =504a(6) =64a(7) =2193a(8) =1474a(9) =5544a(10) =144a(11) =56024a(12) =196a(13) =84912a(14) =83376a(15) =674257a(16) =324a(17) =2833128a(18) =400a(19) =10842624a(20) =3764224a(21) =25404696a(22) =576a(23) =283622136a(24) =1913486a(25) =436839984a(26) =243868120a(27) =2955876880a(28) =900a(29) =13385040624