a(n) = ((n*p)^p - 1)/(n*p-1) where p = prime(n).A392068a(n) = ((n*p)^p - 1)/(n*p-1) where p = prime(n).Terms a(0) =3a(1) =43a(2) =54241a(3) =499738093External referencesoeis: A392068