Composite numbers k such that sigma(k)*(phi(k) + 2) is a square.

Terms

a(0) =28a(1) =90a(2) =156a(3) =184a(4) =374a(5) =1855a(6) =2162a(7) =2170a(8) =2280a(9) =2376a(10) =2415a(11) =2665a(12) =3160a(13) =4970a(14) =5270a(15) =5740a(16) =6402a(17) =6494a(18) =7414a(19) =8400a(20) =9118a(21) =10656a(22) =11155a(23) =12400a(24) =14632a(25) =14910a(26) =15010a(27) =15906a(28) =18183a(29) =18792