[ VCF = \exp\left[-\alpha_15 \Delta t (1 + 0.5\alpha_15 \Delta t + \frac16\alpha_15^2 \Delta t^2 + \dots)\right] ]
=EXP(-B5 * (B3-15) * (1 + 0.5*B5*(B3-15) + (1/6)*B5^2*(B3-15)^2)) astm table 54 excel