Most Nikon lenses I am familiar with are numbered 2.8 - 2 - 1.4 or 1.2 for the larger apertures, but there is a 1.8 50mm so it's not universal, that one goes 2.8 - 1.8.

No Nikkor's I've used have click stops at anything other than full stop increments, though the lens can be set to any intermediate point.