Numbers k in A020487 with arithmetic derivative k' (A003415) in A020487.

Terms

a(0) =4a(1) =256a(2) =500a(3) =625a(4) =2500a(5) =4225a(6) =11664a(7) =12800a(8) =14580a(9) =81920a(10) =250000a(11) =262144a(12) =364500a(13) =531441a(14) =800000a(15) =2125764a(16) =4734976a(17) =11943936a(18) =27541504a(19) =64000000a(20) =84050000a(21) =107868672a(22) =156250000a(23) =162542848a(24) =195312500a(25) =253472000a(26) =512635136a(27) =544195584a(28) =607642880a(29) =701146368