Perfect Delaunay polytopes in low dimensions.
We show that the generalized Fermat equations with signatures (5,5,7), (5,5,19), and (7,7,5) (and unit coefficients) have no non-trivial primitive integer solutions. Assuming GRH, we also prove the non-existence of non-trivial primitive integer solutions for the signatures (5,5,11), (5,5,13), and (7,7,11). The main ingredients for obtaining our results are descent techniques, the method of Chabauty-Coleman, and the modular approach to Diophantine equations.
Let be the sequence given by and for . In this paper, we show that the only solution of the equationis in positive integers and is .
Let be a real quadratic field with ring of integers . In this paper we analyze the number of -orbits of homothety classes of perfect unary forms over as a function of . We compute exactly for square-free . By relating perfect forms to continued fractions, we give bounds on and address some questions raised by Watanabe, Yano, and Hayashi.