Numbers k for which sigma(k) = k + k'', where k'' is the second derivative of k (A068346).

Terms

a(0) =1a(1) =161a(2) =209a(3) =221a(4) =4265a(5) =12690a(6) =15941a(7) =22217a(8) =24041a(9) =25637a(10) =30377a(11) =38117a(12) =39077a(13) =48617a(14) =49097a(15) =55877a(16) =68441a(17) =73817a(18) =76457a(19) =80357a(20) =88457a(21) =95237a(22) =98117a(23) =99941a(24) =105641a(25) =110057a(26) =115397a(27) =122537a(28) =130217a(29) =131141