Composite numbers k such that sum of proper divisors of k divides 2^k-1.

Terms

a(0) =4a(1) =16a(2) =18a(3) =125a(4) =144a(5) =256a(6) =400a(7) =6489a(8) =27559a(9) =42601a(10) =65536a(11) =105800a(12) =110825a(13) =128975a(14) =129600a(15) =145800a(16) =152775a(17) =200025a(18) =208679a(19) =213444a(20) =226033a(21) =298116a(22) =435600a(23) =649800a(24) =761959a(25) =892561a(26) =1076647a(27) =1248961a(28) =1622225a(29) =1851569