Triangular numbers composed of digits {0,1,9}.

Terms

a(0) =1a(1) =10a(2) =91a(3) =190a(4) =990a(5) =10011a(6) =19110a(7) =19900a(8) =90100a(9) =1911990a(10) =1991010a(11) =1999000a(12) =99991011a(13) =199110990a(14) =199910010a(15) =199990000a(16) =901999101a(17) =1000900911a(18) =1111019091a(19) =19991100990a(20) =19999100010a(21) =19999900000