On numerical approximation: edited by Rudolph E. Langer. 462 pages, [formula omitted] in. Madison, University of Wisconsin Press, 1959. Price, $4.50

Abstract

An Engel series is a sum of the reciprocals of an increasing sequence of positive integers, which is such that each term is divisible by the previous one. Here we consider a particular class of Engel series, for which each term of the sequence is divisible by the square of the preceding one, and find an explicit expression for the continued fraction expansion of the sum of a generic series of this kind. As a special case, this includes certain series whose continued fraction expansion was found by Shallit. A family of examples generated by nonlinear recurrences with the Laurent property is considered in detail, along with some associated transcendental numbers.For a video summary of this paper, please visit https://youtu.be/T7OL_rKI8Z8.