Triangular numbers for which the sum of the digits is a square.

Terms

a(0) =0a(1) =1a(2) =10a(3) =36a(4) =45a(5) =153a(6) =171a(7) =351a(8) =630a(9) =1035a(10) =1431a(11) =2016a(12) =3240a(13) =3321a(14) =4005a(15) =8001a(16) =10440a(17) =13041a(18) =13203a(19) =16110a(20) =21321a(21) =23220a(22) =25200a(23) =67896a(24) =89676a(25) =101025a(26) =105111a(27) =114003a(28) =186966a(29) =187578