Van der Poorten was the author of approximately 180 publications in number theory, on subjects that included Baker's theorem, continued fractions, elliptic curves, regular languages, the integer sequences derived from recurrence relations, and transcendental numbers.
As well as publishing his own research, van der Poorten was noted for his expository writings, among them a paper on Apéry's theorem on the irrationality of ζ(3) and his book on Fermat's last theorem.[REF] .