Cuspidal divisor class groups of non-split Cartan modular curves

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I find an explicit description of modular units in terms of Siegel functions for the modular curves X+ns(pᵏ) associated to the normalizer of a non-split Cartan subgroup of level pᵏ where p=2,3 is a prime. The Cuspidal Divisor Class Group C+ns(pᵏ) on X+ns(pᵏ) is explicitly described as a module over the group ring R = Z[(Z/pᵏZ)*/{± 1}]. In this paper I give a formula involving generalized Bernoulli numbers B₂,ᵪ for |C+ns(pᵏ)|.