Numbers k such that sigma(sigma(k)) is a Fibonacci number.

Terms

a(0) =1a(1) =4a(2) =13228a(3) =19289a(4) =187838a(5) =201255a(6) =281771a(7) =308591a(8) =7391381a(9) =9041581a(10) =9124081a(11) =9589141a(12) =193690242024a(13) =254218445292a(14) =306676216538a(15) =375274847812a(16) =402512534123a(17) =423082506591a(18) =425477274579a(19) =443127377343a(20) =456962010177a(21) =458339382147a(22) =476155178309a(23) =480858185253a(24) =484213195281