Let f(x)=∑鈩?isin;Za鈩?/sub>e2i蟺鈩搙, where and d(k)=∑d|k1 and let fn(x)=f(nx). We show by using a new decomposition of squared sums that, for any K⊂N finite, . If , s>1/2, by only using elementary Dirichlet convolution calculus, we show that for 0<蔚≤2s−1, , where 蟽h(n)=∑d|ndh. From this, we deduce that if f∈BV(T), 銆坒,1銆?0 and , then the series ∑kckfk converges almost everywhere. This slightly improves a recent result, depending on a fine analysis on the polydisc ([1], th. 3) (nk=k), where it was assumed that converges for some 纬>4.