Indices k such that 9 plus the k-th triangular number is a perfect square.

Terms

a(0) =0a(1) =10a(2) =13a(3) =63a(4) =80a(5) =370a(6) =469a(7) =2159a(8) =2736a(9) =12586a(10) =15949a(11) =73359a(12) =92960a(13) =427570a(14) =541813a(15) =2492063a(16) =3157920a(17) =14524810a(18) =18405709a(19) =84656799a(20) =107276336a(21) =493415986a(22) =625252309a(23) =2875839119a(24) =3644237520a(25) =16761618730a(26) =21240172813a(27) =97693873263a(28) =123796799360a(29) =569401620850