Nonprime numbers that divide their second arithmetic derivative.

Terms

a(0) =1a(1) =4a(2) =8a(3) =16a(4) =24a(5) =27a(6) =48a(7) =54a(8) =64a(9) =108a(10) =128a(11) =162a(12) =168a(13) =256a(14) =320a(15) =324a(16) =432a(17) =512a(18) =704a(19) =729a(20) =864a(21) =1024a(22) =1134a(23) =1728a(24) =2048a(25) =2160a(26) =2187a(27) =2192a(28) =2916a(29) =3125