#2550: Webb explain

[Cueball and Ponytail are looking at an advent calendar hanging on a wall in front of them. The advent calendar is loosely tiled with 18 smaller hexagons, numbered from 5 to 22 in no clear order or pattern. They are regularly arranged into a larger hexagonal shape and of the five rows, there are three in the top and bottom ones, as also with each diagonal edge. There are four in each of the other rows, offset symmetrically, with a gap where a fifth could have been in the center of the middle row.]

Cueball: The hexagons are nice.

Cueball: But why does it end at 22?

[The order of the numbers in the advent calendar are as this:]

      5      22      10

 11      15      19      17

14 7 [none] 13 8

  9      16       6      20

     18      21      12

[Caption below the panel:]

Astronomer Advent Calendar