>>10094191you're missing the fact that all trips are contain dubs xxxaaabb is trips not double dubs.
I think the easiest way to talk about this is frequency in a range.
00000000-99999999
if we list out the 2xdubs and trips in order you'll get
00000000,00000011,00000022(this whole set doesnt count because its dubs and hepta zeros) ...,00001100,(skipping 00001111 because its quads),00001122,00002211,(skipping 00002222 because its quads),00002233
meanwhile
00000111,00000222,00000333... there is 8 under 00001000 the first double dubs is 00001100.
the simplification you gave ignores the fact that not all posts containing aa&bb are dubs.
