Numbers whose sum of proper (or aliquot) divisors is a prime.

Terms

a(0) =4a(1) =8a(2) =21a(3) =27a(4) =32a(5) =35a(6) =39a(7) =50a(8) =55a(9) =57a(10) =63a(11) =65a(12) =77a(13) =85a(14) =98a(15) =111a(16) =115a(17) =125a(18) =128a(19) =129a(20) =155a(21) =161a(22) =171a(23) =175a(24) =185a(25) =187a(26) =189a(27) =201a(28) =203a(29) =205