We perform coupled-cluster calculations of the energies and lifetimes of single-particle states around the doubly magic nucleus (16)O based on chiral nucleon-nucleon interactions at next-to-next-to-next-to-leading order. To incorporate effects from the scattering continuum, we employ a Gamow-Hartree-Fock basis. Our calculations for the J(pi)=1/2(+) proton halo state in (17)F and the 1/2(+) state in (17)O agree well with experiment, while the calculated spin-orbit splitting between 5/2(+) and 3/2(+) states is too small due to the lack of three-nucleon forces. Continuum effects yield a significant amount of additional binding energy for the 1/2(+) and 3/2(+) states in (17)O and (17)F.