5826
This is exactly the sort of pattern we get asked for on a daily basis - simple round neck with a drop sleeve. It looks just great fitting as it's supposed to but the wide size range also gives the options for some super oversized stuff which I hear the kids are into. I would not know.
This will work just fabulously in any chunky yarn! You'll need 5.5mm and 6mm needles, along with six buttons for the cardigan.