Numbers k such that there is a proper divisor d of k satisfying sigma(d)=k.

Terms

a(0) =1a(1) =12a(2) =56a(3) =360a(4) =992a(5) =2016a(6) =16256a(7) =120960a(8) =131040a(9) =1571328a(10) =8714160a(11) =67100672a(12) =94279680a(13) =182131200a(14) =571963392a(15) =1379454720a(16) =4428914688a(17) =5517818880a(18) =17179738112a(19) =70912195200a(20) =153003540480a(21) =159991977600a(22) =175445913600a(23) =265734881280a(24) =274877382656a(25) =612014161920