Triangular numbers whose 10's complements are squares.

Terms

a(0) =1a(1) =6a(2) =36a(3) =91a(4) =2775a(5) =3916a(6) =8911a(7) =394716a(8) =785631a(9) =889111a(10) =961191a(11) =1456071a(12) =5539456a(13) =7704775a(14) =13825911a(15) =39502716a(16) =56440000a(17) =76156311a(18) =88891111a(19) =1507087351a(20) =1764981991a(21) =2530200816a(22) =2743515775a(23) =3950582716a(24) =5119859836a(25) =5468017600