Abstract.We study the level m-Demazure flag of a level ℓ-Demazure module for sl2 [t]. We define the generating series A ℓ→m n (x, q) which encodes the q-multiplicity of the level m Demazure module of weight n. We establish two recursive formulae for these functions. We show that the specialization to q = 1 is a rational function involving the Chebyshev polynomials. We give a closed form for A ℓ→ℓ+1 n (x, q) and prove that it is given by a rational function. In the case when m = ℓ + 1 and ℓ = 1, 2, we relate the generating series to partial theta series. We also study the specializations A 1→3 n (q k , q) and relate them to the fifth order mock-theta functions of Ramanujan.