This is d'Hondt? The party with the highest V/(s+1) gets the next seat and then its quota is recalculated because it's "s" has changed?

Yes, 13% there is the d'Hondt threshold effect ... but suppose that 13% was split 8% 4% and minor parties ...

36 [1] 18 [1] 18 [2] 12 [2] 12 [3]
32 [0] 32 [1] 16 [1] 16 [2] 08 [2]
08 [0] 08 [0] 08 [0] 08 [0] 08 [0]
04 [0] 04 [0] 04 [0] 04 [0] 04 [0]

The threshold for a minor party deputy there is 12%, the largest vote share divided by the plurality of 3. Hence the "regional" 3rd parties doing better.

That's why a wedge that shifts voters from the leading party in a district to a 3rd party that already has a toehold is particularly appealing under d'Hondt, since it reduces both sides of the gap to the threshold.

That's also why Sainte-Laguë, which uses V/(1+2*s), is more favorable to medium size 3rd parties:

36 [1] 12 [1] 12.0 [2] 07.2 [2] 07.2 [2]
32 [0] 32 [1] 10.3 [1] 10.3 [2] 06.4 [2]
08 [0] 08 [0] 08.0 [0] 08.0 [0] 08.0 [1]
04 [0] 04 [0] 04.0 [0] 04.0 [0] 04.0 [0]


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.