Numbers k such that sigma(k) - usigma(k) is a square and sets a new record for such squares.

Terms

a(0) =1a(1) =18a(2) =28a(3) =40a(4) =84a(5) =120a(6) =208a(7) =372a(8) =424a(9) =552a(10) =624a(11) =900a(12) =1152a(13) =1848a(14) =2784a(15) =3904a(16) =4488a(17) =4992a(18) =7448a(19) =7896a(20) =9120a(21) =11712a(22) =13720a(23) =14280a(24) =19920a(25) =22344a(26) =26040a(27) =27144a(28) =37920a(29) =41160