#1**+1 **

I would be considering the connectors and rods seperately and then add them together

connectors

row 0 1

row 1 2

row 2 3

etc

and add them up

rods

row 1 2

row 2 4

there will be 2 rods off each connector so row 3 will have 2*3=6 connectors

etc

then add them up.

If you have done arithmetic progression you can add these with formula but there are not many so you can just add them all up in you head or on paper.

That is a more than ample hint :)

Melody Oct 26, 2019