On perfect powers that are sums of cubes of a nine term arithmetic progression

Nirvana Coppola, Mar Curcó-Iranzo, Maleeha Khawaja, Vandita Patel, Özge Ülkem

Published 2023-07-04Version 1

We prove that the only integral solutions to the equation $(x-4r)^3 + (x-3r)^3 + (x-2r)^3+(x-r)^3 + x^3 + (x+r)^3+(x+2r)^3 + (x+3r)^3 + (x+4r)^3 = y^p$ satisfy the condition $xy=0$ if $p\geq 5$ is a prime. We also show that there are infinitely many solutions for $p=2$ and $p=3$. This is a natural continuation of previous work carried out by A. Arg\'{a}ez-Garc\'{i}a and the fourth author. We use an amalgamation of existing methods to overcome the increased computational challenge. Most notable is a significant computational efficiency obtained through appealing to Bilu, Hanrot and Voutier's Primitive Divisor Theorem and the method of Chabauty, as well as employing a Thue equation solver earlier on.