a(n) = sigma_3(n)^2.

Terms

a(0) =1a(1) =81a(2) =784a(3) =5329a(4) =15876a(5) =63504a(6) =118336a(7) =342225a(8) =573049a(9) =1285956a(10) =1774224a(11) =4177936a(12) =4831204a(13) =9585216a(14) =12446784a(15) =21911761a(16) =24147396a(17) =46416969a(18) =47059600a(19) =84603204a(20) =92775424a(21) =143712144a(22) =148060224a(23) =268304400a(24) =248094001a(25) =391327524a(26) =417793600a(27) =630612544a(28) =594872100