A method to find an analytic function passing through any countable set of points is provided, along with a proof of analyticity. This method is based on the fact that the formula f (n) = dⁿdtⁿ ₊=₀^ f (k) tᵏk! ₓ=₀ can be extended using the Riemann-Liouville fractional derivative _Dₓ^z (defined in the introduction), enabling evaluation of the derivative of any order z C: f (z) = _Dₓ^z ₊=₀^ f (k) tᵏk! ₓ=₀. This provides a simple formula to interpolate an arbitrary set of points of the form (n, f (n) ), n N. Generalizations are provided to interpolate any countable set of points, given appropriate conditions.
Alessandro Bartocetti (Mon,) studied this question.