A playground is being designed where children can interact with their friends in certain combinations.
If there is 1 child, there can be 0 interactions.
If there are 2 children, there can be only 1 interaction.
If there are 3 children, there can be 5 interactions.
If there are 4 children, there can be 14 interactions.
Which recursive equation represents the pattern?
an = an - 1 + 2(n - 1)
an = an - 1 + (n - 1) 2
an = an - 1 + 2(n - 1)
an = an - 1 + (2n - 1)