1 counter, 1 yellow surrounded by circle of 6 blue counters, above surrounded by 12 red counters Take a counter and surround it by a ring of other counters that MUST touch two others.
How many are needed?
line of counters: 1 yellow, 2 blue, 3 red, 4 green, 5 light blue
Imagine surrounding this ring with more counters.
How many counters are needed?
Were you right?
What about a bigger ring?
And another? And another?
Or why not just lay them down according to some rule?
What will be the 30th counter to be laid?
The 100th? The 200th?