Numbers k such that sigma_2(k)/k and sigma_4(k)/k are integers.

Terms

a(0) =1a(1) =84a(2) =435708a(3) =986076a(4) =1441188a(5) =6066396a(6) =7407036a(7) =16763292a(8) =18735444a(9) =78863148a(10) =260855028a(11) =318502548a(12) =1340673516a(13) =3391115364a(14) =10829086632a(15) =45076171140a(16) =45582899544a(17) =57648961188a(18) =77314641768a(19) =128293717860a(20) =149098104540a(21) =174975241896a(22) =440359518060a(23) =461191689504