Mock Rib (over an odd number of sts)
Note: the instructions below are a generic description of how to execute this stitch pattern. For a single repeat, you'd only need three stitches but you'd have a VERY narrow piece! In the example shown, there are fifteen repeats of the stitch, so to make a swatch that looks like the one shown, you need to cast on 45 stitches (15 x the multiple of 3 stitches needed for a single repeat of the pattern.)
Row 1 (RS) K1, *p1, k1; rep from * to end.
Row 2 Purl.
Rep rows 1 and 2.
Stitch directions reproduced with permission, from Vogue Knitting Stitchionary: Volume One, Sixth & Spring Books, 2005