Ditto for "tre": https://docs.arduino.cc/retired/boards/arduino-tre

It looks like they haven't used "quattro" themselves, but a popular Arduino-based robotics project has, so using it for a new board would be confusing.

They've used "cinque" too: https://hackaday.com/2017/05/20/arduino-cinque-the-risc-v-es...

"Sei" isn't used, but it'd cause confusion when people search for how to enable interrupts on Arduinos.

So I think "sette" would be the next good candidate if they wanted to name it after a number.