Teams Req'd To Enter Season w/ 2-Cars?

BoogerMac

500RPM
Jul 23, 2015
573
205
I'm not a die-hard F1 fan, so pardon my ignorance. Are teams required to enter every season with multiple cars? Is it possible for a new outfit to enter F1 with a single car on the grid? Has this been done previously? On the flip-side, has any team ever entered more than two cars into a season?

Thanks in advance.