Hyperperfect numbers: k = m*(sigma(k) - k - 1) + 1 for some m > 1.

Terms

a(0) =21a(1) =301a(2) =325a(3) =697a(4) =1333a(5) =1909a(6) =2041a(7) =2133a(8) =3901a(9) =10693a(10) =16513a(11) =19521a(12) =24601a(13) =26977a(14) =51301a(15) =96361a(16) =130153a(17) =159841a(18) =163201a(19) =176661a(20) =214273a(21) =250321a(22) =275833a(23) =296341a(24) =306181a(25) =389593a(26) =486877a(27) =495529a(28) =542413a(29) =808861