Numbers n such that the sum of the proper divisors of n and n+1 equals either n or n+1.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =7a(6) =16a(7) =28a(8) =31a(9) =38a(10) =127a(11) =256a(12) =278a(13) =469a(14) =1298a(15) =3477a(16) =7298a(17) =7525a(18) =8191a(19) =13969a(20) =19909a(21) =26738a(22) =31492a(23) =65536a(24) =99381a(25) =131071a(26) =357698a(27) =524287a(28) =20742482a(29) =33550336