Indices of the triangular numbers in A189475.

Terms

a(0) =1a(1) =2a(2) =6a(3) =18a(4) =54a(5) =29a(6) =182a(7) =546a(8) =1638a(9) =4914a(10) =1407a(11) =1599a(12) =726a(13) =581a(14) =945a(15) =16362a(16) =1536a(17) =49278a(18) =2175a(19) =7077a(20) =22238a(21) =4224a(22) =6266a(23) =10632a(24) =21440a(25) =38454a(26) =21189a(27) =12801a(28) =219138a(29) =47039