a(n) = Sum_{d|n} d^(2*d-1).A359732a(n) = Sum_{d|n} d^(2*d-1).Terms a(0) =1a(1) =9a(2) =244a(3) =16393a(4) =1953126a(5) =362797308a(6) =96889010408External referencesoeis: A359732