Note: Given the elasticity of brioche, you should cast on and bind off very loosely

Knit version.
Cast on an even number of sts.
Set-up Row: Knit all sts.
Pattern Row: * K1, K1b; repeat from * to end.
Repeat Pattern Row until you have reached your desired length.

Purl version.
Cast on an even number of sts.
Set-up Row: Purl all sts.
Pattern Row: * P1, P1b; repeat from * to end.
Repeat Pattern Row until you have reached your desired length.

Abbreviations:
– K, P: Knit, purl.
– K1b: Knit 1 in the row below.
Insert needle through center of st 1 row below next st and knit, slipping st above off needle at same time.
– P1b: Purl 1 in the row below.
Insert needle through center of st 1 row below next st and purl, slipping st above off needle at same time.