Suzette crochet stitch
A US sc and dc share one insertion point, then the next base stitch is skipped.
Counted practice swatch
Chain 22, an even number.
Work the repeat
Row 1: (sc, dc) in second chain; [skip 1 ch, (sc, dc) in next ch] 9 times; skip 1 ch, sc in last ch (21 stitches). Row 2: ch1, turn, (sc, dc) in first sc; [skip next dc, (sc, dc) in next sc] 9 times; skip next dc, sc in final sc. Repeat.
Read the fabric
The terminal sc is an edge stitch. Each pair sits in a previous sc, while each previous dc is skipped.