G Freitas,
J Lelis, E Silva - arXiv preprint arXiv:2203.11755, 2022 - arxiv.org
In 1989, Ming Luo\cite {L2} showed that the Fibonacci number $ U_n $ is Triangular if and
only if $ n=\pm1, 2, 4, 8, 10$. For this, he established a Jacobi Symbol Criterion. Moreover …