Numbers k such that sigma(k) divides k^2.

Terms

a(0) =1a(1) =6a(2) =28a(3) =120a(4) =364a(5) =496a(6) =672a(7) =840a(8) =1080a(9) =1488a(10) =1782a(11) =2280a(12) =3276a(13) =3472a(14) =7440a(15) =8128a(16) =8736a(17) =11880a(18) =12400a(19) =18360a(20) =20832a(21) =24384a(22) =25296a(23) =26208a(24) =30240a(25) =30256a(26) =32760a(27) =35640a(28) =37200a(29) =56896