Oblong numbers n such that sigma(n) is a triangular number.

Terms

a(0) =2a(1) =12a(2) =56a(3) =342a(4) =992a(5) =16256a(6) =17822a(7) =169332a(8) =628056a(9) =1189190a(10) =2720850a(11) =11085570a(12) =35599122a(13) =67100672a(14) =1147210770a(15) =1317435912a(16) =1707135806a(17) =7800334080a(18) =11208986256a(19) =13366943840a(20) =17109032402a(21) =17179738112a(22) =46343540900a(23) =58413331032a(24) =83717924940a(25) =204574837700a(26) =274877382656a(27) =445968192672a(28) =589130699852