sigma(n) + n is a square.

Terms

a(0) =33a(1) =90a(2) =385a(3) =420a(4) =649a(5) =900a(6) =1441a(7) =1464a(8) =1480a(9) =1729a(10) =2025a(11) =2616a(12) =3168a(13) =3588a(14) =3984a(15) =4005a(16) =4873a(17) =5049a(18) =5185a(19) =6225a(20) =7153a(21) =7585a(22) =8740a(23) =9060a(24) =10285a(25) =11080a(26) =12280a(27) =12609a(28) =13914a(29) =14809