a(n) = Sum_{d|n} d^(2*(d-1)).A308753a(n) = Sum_{d|n} d^(2*(d-1)).Terms a(0) =1a(1) =5a(2) =82a(3) =4101a(4) =390626a(5) =60466262a(6) =13841287202External referencesoeis: A308753