Values of n such that sigma(n)-2n (the abundance of n) is a (nonnegative) square.

Terms

a(0) =6a(1) =12a(2) =28a(3) =70a(4) =88a(5) =108a(6) =168a(7) =220a(8) =348a(9) =496a(10) =550a(11) =580a(12) =726a(13) =748a(14) =798a(15) =910a(16) =918a(17) =952a(18) =1032a(19) =1120a(20) =1200a(21) =1240a(22) =1504a(23) =1644a(24) =1672a(25) =1840a(26) =1888a(27) =2140a(28) =2205a(29) =2392