Indices k such that 6 plus the k-th triangular number is a perfect square.

Terms

a(0) =2a(1) =4a(2) =19a(3) =29a(4) =114a(5) =172a(6) =667a(7) =1005a(8) =3890a(9) =5860a(10) =22675a(11) =34157a(12) =132162a(13) =199084a(14) =770299a(15) =1160349a(16) =4489634a(17) =6763012a(18) =26167507a(19) =39417725a(20) =152515410a(21) =229743340a(22) =888924955a(23) =1339042317a(24) =5181034322a(25) =7804510564a(26) =30197280979a(27) =45488021069a(28) =176002651554a(29) =265123615852