On a Class of Iteration Formulas and Some Historical Notes The class of iteration formulas obtainable by rational approximations of "Euler's formula" is derived with the corresponding error estimates. Some historical notes on iterative procedures are followed by a derivation of Euler's formula with the associated error estimate in a new notation which simplifies the error estimate and suggests generalizations. The final section considers the Pade approximants to the "Euler polynomial" and shows how a number of known formulas may be derived from this unified approach. There is a short discussion of the "best" formula. CACM June, 1961 Traub, J. F. CA610606 JB March 16, 1978 10:36 PM 319 4 319 319 5 319 319 5 319 319 5 319 380 5 319