I have my background change color when value is entered, but how do I add numerous value

For example v==3 turns red.  I would like to turn red if 9, 15, 21, 25, 27, 29 is entered.   How do I go about doing this?  Do I have to do invidual lines or do I put && between values?

My code knowledge is about .01.. I just find what I'm looking for online and tweak it.

var v = Number(event.value);
if (v==1) {event.target.fillColor = color.green;}
else if (v==2) {event.target.fillColor = color.yellow;}
else if (v==3) {event.target.fillColor = color.red;}
else event.target.fillColor = color.white;