Using smaller needles and B, cast on 41 sts.
Knit 4 rows. Cut B.
Change to larger needles and A; knit 2 rows.
Using D as MC and A as CC and working both colors in garter st–mosaic pat, work 24-row Hashtag pat. Cut D.
Using C as MC in garter st—mosaic pat and A as CC in St st-mosaic pat, work 24-row Hashtag pat twice. Cut C.
Using B as MC and A as CC and working both colors in St st–mosaic pat, work 24-row Hashtag pat. Cut A and B.
Change to smaller needles and D; knit 1 row. Dec row (WS): [K6, k2tog] 5 times, k1—36 sts. Knit 3 rows. Bind off loosely kwise.
Weave in ends. Block. Sew seam.