Numbers k such that sigma_2(k)*sigma_1(k)/sigma_0(k) is a perfect square.

Terms

a(0) =1a(1) =4a(2) =529a(3) =2116a(4) =2583a(5) =3249a(6) =3346a(7) =6150a(8) =10332a(9) =12474a(10) =12792a(11) =12996a(12) =28224a(13) =38240a(14) =59245a(15) =85905a(16) =91035a(17) =103607a(18) =142560a(19) =176382a(20) =212949a(21) =236980a(22) =249744a(23) =343620a(24) =360096a(25) =364140a(26) =379050a(27) =414428a(28) =450840a(29) =751530