Numbers k such that sopfr(k) = ud(k), where sopfr = A001414 and ud = A034444.

Terms

a(0) =2a(1) =5460a(2) =9240a(3) =253890a(4) =358050a(5) =387090a(6) =395850a(7) =429660a(8) =440895a(9) =458850a(10) =468930a(11) =475020a(12) =529074a(13) =550620a(14) =574770a(15) =629850a(16) =669900a(17) =755820a(18) =788970a(19) =803880a(20) =821100a(21) =828828a(22) =895356a(23) =896610a(24) =948090a(25) =985320a(26) =986700a(27) =1065900a(28) =1123122a(29) =1168860