Largest prime dividing sigma(4,n).

Terms

a(0) =17a(1) =41a(2) =13a(3) =313a(4) =41a(5) =1201a(6) =257a(7) =73a(8) =313a(9) =7321a(10) =41a(11) =14281a(12) =1201a(13) =313a(14) =41a(15) =41761a(16) =73a(17) =3833a(18) =313a(19) =1201a(20) =7321a(21) =139921a(22) =257a(23) =601a(24) =14281a(25) =193a(26) =1201a(27) =353641a(28) =313a(29) =1129