Making use of the coupled cluster variant CCSD(T) in conjunction with Dunning's cc-pVTZ basis set, equilibrium structures and complete harmonic force fields have been calculated for the linear carbon chains of type C2n+1 with n = 5-9. With the exception of C-3, which is a well-known "floppy" molecule with an extremely shallow bending potential, all members of the C2n+1 series up to C-19 appear to behave like fairly normal semirigid molecules. The IR active bending vibrations of lowest wavenumber for C-17 and C-19, which may be of interest to forthcoming far-infrared astronomy, are predicted to occur at 13.1 and 11.1 cm(-1), respectively, with corresponding absolute IR intensities of 6.6 and 5.9 km mol(-1). Huge IR intensities are calculated for one antisymmetric stretching vibration per chain (19 948, 29 632, and 30 040 km mol(-1) for C-15, C-17, and C-19, respectively). A quantitative description of these vibrations may require the explicit consideration of anharmonicity effects and electronic structure calculations going beyond CCSD(T).