#2956: Number Line Branch

XKCD comic, described below.
Transcript

[A diagram reminiscent of both the number line and a transit system diagram. The line starts at the left and goes right through points labeled 0, 1, 2, and 3, at which point there is a split into two branches. The top branch continues: 4, 5, 6, 7, 8, 9, 10, …. The bottom branch is shorter, labeled with five curious glyphs: a square, a near-vertical line with two short horizontal lines jutting out from it, a phi-like/lollipop symbol, a spiral, and a delta/triangle symbol.]

[Caption below the panel:]

Good news!

After thousands of years, mathematicians have finally opened a second branch on the number line to reduce congestion.

(Sourced from explainxkcd.com)

Attention all passengers: This is an express sequence to infinity. If your stop is not a power of two, please disembark now.

ExplainOriginal