How can you arrange 7 dots so that there are 6 lines of 3 colinear dots?

1 Answer
Jun 24, 2016

See explanation...

Explanation:

Here's one solution:

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Bonus

This is an example of a problem that is very difficult to solve in the general case. The maximum number lines of 3 dots in n dots follows the sequence (catalogued as A003035 in the online encyclopedia of integer sequences) that starts:

0,0,1,1,2,4,6,7,10,12,16,19,22,26

The next number in the sequence is known to be 31 or 32, but it is an unsolved problem which one it is.