Here is a tip, if i(t) has not been done before.
Take products, c, that have odd x+n. And even n.
Take one from x+n.
8 triangles.
Create a table.
What does f and 2(n-1) contribute?
Because the tips of all 8 triangles are from (n-1)(n-1) - 1.
Find the pattern from large to small.
There are h families!
Avoid the 13th step of AA.