Numbers n for which n*n'/(n+n') is an integer, where n' is the arithmetic derivative of n.

Terms

a(0) =1a(1) =4a(2) =64a(3) =80a(4) =108a(5) =270a(6) =351a(7) =432a(8) =729a(9) =768a(10) =864a(11) =2916a(12) =5184a(13) =5832a(14) =6250a(15) =6912a(16) =12096a(17) =13500a(18) =16384a(19) =25600a(20) =32832a(21) =34992a(22) =37500a(23) =39366a(24) =43200a(25) =46656a(26) =50000a(27) =73008a(28) =74304a(29) =81648