Aliquot Sequences
Juan L. Varona's work on aliquot sequences examines sequences with start values up to 10000, and traces them to large composite values.
Aliquot Sequences
Results and software from Paul Zimmermann, addressing the Catalan Conjecture and working on the difficult "Lehmer Five" sequences.
Aliquot Sequences
Aliquot sequences arise in iterating the sum-of-divisors function s. Bosma has calculated tables up to start value 50,000 and 80 digits.
Aliquot Sequences
Statistics by Wolfgang Creyaufmueller, including many tables and links to factoring sites and software.
Amicable Numbers
Observations on amicable pairs and their distribution, including Harshad and Happy Amicable pairs.
Multiply Perfect Numbers
Up-to-date information on multiperfect numbers and searchable database maintained by Achim Flammenkamp.
On a Generalization of Perfect Numbers
J. L. Pe introduces perfect numbers relative to an arithmetical function f. Under this scheme, the usual perfect numbers are just one among many species of "f-perfect numbers". Sev…
Perfect Numbers
Harry J. Smith's pages of the mathematics behind perfect numbers, aliquot sequences and Mersenne numbers. Includes program listings and e-mail archives.