M.A. Gopalan, K. Geetha, Manju Somanath, Special Dio 3 - Tuples, BSMaSS Volume 10, The Bulletin of Society for Mathematical Services and Standards (Volume 10)
    We search for three distinct polynomials with integer coefficient such that the product of anytwo members of the set minus their sum and increased by a non-zero integer (or polynomial withinteger coefficient) is a perfect square.
    Centered Polygonal Numbers, Dio 3 - Tuples, Pell Equation, Polygonal Numbers