December 27th, 2022

New record for the largest known amicable pair: a 56259-digit pair was added today!

November 1st, 2019

The BOINC project to find all amicable numbers up to 1020 is complete! A new BOINC search to find all amicable numbers up to 1021 has started:

August 16th, 2017

The BOINC project to find all amicable numbers up to 264 is complete! A new BOINC search to find all amicable numbers up to 1020 has started:

June 28th, 2017

New record for the largest known amicable pair: a 56250-digit pair was added today. This pair was found by Paul Jobling.

January 30th, 2017

A distributed BOINC project to find all amicable pairs with smaller member below 264 has started. Everyone can join it:

August 16th, 2016

All amicable pairs with smaller member below 1018 are now known! There are 901,312 such pairs, 485,789 of them are 18-digit. It took 3.5 months (20 PCs running 24/7) to extend the border from 1017.

May 10th, 2016

New article added: A collection of methods for finding type (i, 1) amicable pairs/breeders

April 11th, 2016

The 1,000,000,000th amicable pair has been submitted today!!!

April 4th, 2016

Submission form now uses compression to speed up huge submissions.

March 7th, 2016

The first type (8, 1) amicable pair has been found! Both pair members are 80 digits long:

81 Chernykh 2016

Type (i, 1) amicable pairs have a long history: Each step is exponentially harder to take, so it took another 15 years to find the first (8, 1) amicable pair.

January 30th, 2016

The first examples of amicable pairs where the two members have different smallest prime factors have been found!
First such pair was found on October 8th, 2015 but went unnoticed until now. Today there are 7 such pairs known:

X43 Chernykh 08 Oct 2015 22:54:20 GMT

X43 Chernykh 02 Nov 2015 10:54:58 GMT

54 Chernykh 26 Oct 2015 17:32:43 GMT

X43 Chernykh 08 Jan 2016 10:14:39 GMT

X43 Chernykh 29 Nov 2015 07:59:53 GMT

X54 Chernykh 31 Oct 2015 09:54:31 GMT

X54 Chernykh 09 Jan 2016 01:57:14 GMT

January 20th, 2016

Fixed downloading of very large files. Files larger than 500 MB are now split into parts.

January 19th, 2016

The site moved to a new, much better server. Submission form is operational again.

December 20th, 2015

New article added: A million new amicable pairs every day: some new methods for finding amicable pair breeders

December 8th, 2015

Amicable pair submission form is updated:

November 11th, 2015

New article added: Amicable pairs: searching for them efficiently

October 30th, 2015

The first amicable pair of type (10,x) found:

10,5 Chernykh 2015

All other currently known amicable pairs have type (i,j) where both i and j are less than 10.

October 21st, 2015

New record for the largest known amicable pair: a 43145-digit pair was added today.
This pair was originally found by Andrew Walker and Paul Jobling on September 26th, 2011.

October 14th, 2015

New record even-even amicable pair with smallest known m/n ratio found:

X73 Chernykh 2015

The ratio is ~0.60512272, previous record ratio was ~0.6468 for the pair (35049418250,54192685558)

October 12th, 2015

Submission form was updated: it will now provide a download link to a list of all new amicable pairs upon submission.

October 4th, 2015

I've added all pairs from Jan Munch Pedersen's site and Patrick Costello's site to this amicable pairs database.
The site is up and running now!

Sergei Chernykh