Trinity StitchVideo Tutorial: Trinity Stitch Crochet
The multiple is 2 + 1.
You put your hook through the next chain and pull up a loop, leave the loop on your hook and repeat the same steps two more times. You will have 4 loops on your hook. Wrap the yarn over your hook and pull through all 4 loops. Chain 1 to secure. Chain 1 again. Each stitch will share a chain loop with the previous stitch.