Sorry for throwing a spanner in the works Honchey,
I found my pineapple quilt (yes there are not too many patterns I have not tried) made this over 16 years ago and it was paper pieced, drew up the block last night using graph paper and using the method GGal gave us I made a pineapple block this morning and it is 12 1/2 inches. I did this before going to the Doc's.
I started with a 2 1/2 inch square and my strips were cut at 1 1/2 inches, if you look at my block you will notice I have 5 rounds of background fabric and 5 rounds of main fabric. So the maths should work. The corner triangle of the main fabric I cut a 5 1/2 inch square and cut once on the diagonal.
GGal is this what you were thinking of.
Ok I am going to crawl into bed right now, feeling a little sore and sorry for myself. The doc did a little excision and I have 6 stitches in my cheek