A sequence of nine almost equidistant quadrupole transitions is observed in 137Nd. The sequence represents an extremely regular rotational band that extends to a spin of about 75/2 and an excitation energy of ≈4.5 MeV above yrast. Cranked mean-field calculations of the Nilsson-Strutinsky type suggest an oblate shape for the band. They reproduce the observed I(I + 1) dependence of the rotational energy whereas predicting a pronounced decrease in the deformation, which is the hallmark of antimagnetic rotation.