On $a$-$F$ dimensional interpolation

A dimensional interpolation between the free energy and conformal anomaly on spheres is derived for free scalar and spinor fields on the basis of standard field theory. The regularisation used is an extension of one by Candelas and Weinberg. It yields a (known) simple integral which is shown to be identical to the interpolations introduced by Giombi and Klebanov using earlier AdS/CFT results. The extension to GJMS--type higher derivatives is made with a hint of a possible, kinematic resolution of the non--minimal Type-B mismatch being presented. Another form of the sphere conformal anomaly is given.