The answer is YES. We prove a more general statement; suppose that N=C∪D is an arbitrary decomposition of N into two disjoint sets. Then there exists a sequence (an)n=1∞ such that ∑n=1∞anp is convergent for p∈C and divergent for p∈D. Define Ck=C∩[1,k] and Dk∩[1,k]. Lemma. For every positive integer k there exists a positive integer Nk and a sequence Xk=(xk,1,…,xk,Nk) of complex numbers with the following properties: (a) For p∈Dk, we have ∣∑j=1Nkxk,jp∣≥1. (b) For p∈Ck, we have ∑j=1Nkxk,jp=0; moreover, ∣∑j=1mxk,jp∣≤k1 holds for 1≤m≤Nk. Proof. First we find some complex numbers z1…,zk with ∑j=1kzjp={01p∈Ckp∈Dk. As is well-known, this system of equations is equivalent to another system σν(z1,…,zk)=wν(ν=1,2,…,k) where σν is the ν th elementary symmetric polynomial, and the constants wν are uniquely determined by the Newton-Waring-Girard formulas. Then the numbers z1,…,zk are the roots of the polynomial zk−w1zk−1+−…+(−1)kwk in some order. Now let M=⌈max1≤m≤k,p∈Ck∣∑j=1mzjp∣⌉ and let Nk=k⋅(kM)k. We define the numbers xk,1…,xk,Nk by repeating the sequence (kMz1,kMz2,…,kMzk) (kM)k times, i.e. xk,ℓ=kMzj if ℓ≡j(modk). Then we have ∑j=1Nkxk,jp=(kM)k∑j=1k(kMzj)p=(kM)k−p∑j=1kzjp then from (1) the properties (a) and the first part of (b) follows immediately. For the second part of (b), suppose that p∈Ck and 1≤m≤Nk; then m=kr+s with some integers r and 1≤s≤k and hence ∣∑j=1mxk,jp∣=∣∑j=1kr+∑j=kr+1kr+s∣=∣∑j=1s(kMzj)p∣≤(kM)pM≤k1. The lemma is proved. Now let Sk=N1…,Nk (we also define S0=0 ). Define the sequence (a) by simply concatenating the sequences X1,X2,…: (a1,a2,…)=(x1,1,…,x1,N1,x2,1,…,x2,N2,…,xk,1,…,xk,Nk,…) aSk+j=xk+1,j(1≤j≤Nk+1). If p∈D and k≥p then ∣∑j=Sk+1Sk+1ajp∣=∣∑j=1Nk+1xk+1,jp∣≥1. By Cauchy's convergence criterion it follows that ∑anp is divergent. If p∈C and Su<n≤Su+1 with some u≥p then ∣∑j=Sp+1nanp∣=∣∑k=p+1u−1∑j=1Nkxk,jp+∑j=1n−Su−1xu,jp∣=∣∑j=1n−Su−1xu,jp∣≤u1. Then it follows that ∑n=Sp+1∞anp=0, and thus ∑n=1∞anp=0 is convergent.