Unlike a 4, a triple can achieve primary and secondary balance. A 6 acts as two triples, working in mirror image, to cancel out the rocking couple of a 3. Not sure how a 9 would work!

From my apprentice days perfectly balanced engines are straight 6 straight 8, V8 V 12 and W 12, much depends on the firing V6 is just not at any angle but V12 is at any angle. https://www.caranddriver.com/features/a151...s-feature/ though this is a USA derived link and may not completely examine all configurations but it would seem a perfectly balanced 3 would be a star formation as in a 3 phase electric motor my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

One surprising result of fitting a 4 cylinder diesel to a narrow boat is that the crockery in the cupboards often picks up the resonate frequency of a 4 and will buzz in sympathy. Likewise, the tips of handlebars on a 4 cylinder motorcycle can send little fingers to sleep.

Fit a triple to either and the problem goes away

My wife's Suzuki swift 1.0 has a three cylinder turbo petrol and it is certainly very smooth. Being auto it sits at about 1800 revs most of the time. 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE