Triangular numbers representable as 2^x + 2^y.

Terms

a(0) =3a(1) =6a(2) =10a(3) =36a(4) =66a(5) =136a(6) =528a(7) =2080a(8) =8256a(9) =32896a(10) =131328a(11) =524800a(12) =2098176a(13) =8390656a(14) =33558528a(15) =134225920a(16) =536887296a(17) =2147516416a(18) =8590000128a(19) =34359869440a(20) =137439215616a(21) =549756338176