Properties based on the sum-of-divisors function s(n), including perfect and multiperfect numbers, aliquot sequences, amicable pairs and sociable chains.
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Sites 9
Sequences with initial term up to 10,000, by Christophe Clavier.
Aliquot sequences arise in iterating the sum-of-divisors function s. Bosma has calculated tables up to start value 50,000 and 80 digits.
Juan L. Varona's work on aliquot sequences examines sequences with start values up to 10000, and traces them to large composite values.
Results and software from Paul Zimmermann, addressing the Catalan Conjecture and working on the difficult "Lehmer Five" sequences.
Statistics by Wolfgang Creyaufmueller, including many tables and links to factoring sites and software.
Observations on amicable pairs and their distribution, including Harshad and Happy Amicable pairs.
Up-to-date information on multiperfect numbers and searchable database maintained by Achim Flammenkamp.
Definitions and references.
A detailed history of the quest for perfect numbers, from Euclid to their present-day Mersenne discoveries.
A detailed history of the quest for perfect numbers, from Euclid to their present-day Mersenne discoveries.
Sequences with initial term up to 10,000, by Christophe Clavier.
Observations on amicable pairs and their distribution, including Harshad and Happy Amicable pairs.
Up-to-date information on multiperfect numbers and searchable database maintained by Achim Flammenkamp.
Aliquot sequences arise in iterating the sum-of-divisors function s. Bosma has calculated tables up to start value 50,000 and 80 digits.
Juan L. Varona's work on aliquot sequences examines sequences with start values up to 10000, and traces them to large composite values.
Results and software from Paul Zimmermann, addressing the Catalan Conjecture and working on the difficult "Lehmer Five" sequences.
Definitions and references.
Statistics by Wolfgang Creyaufmueller, including many tables and links to factoring sites and software.
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February 16, 2020 at 19:22:05 UTC
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