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This page collects all known primes and probable
primes (PRPs) of the form xy + yx. Most of the information
is taken from the
original page by Paul Leyland, which was unfortunately abandoned in
2006.
Ranges being searched
|
xmin
|
xmax
|
Searched by
|
Reserved
|
Completed
|
PRPs
|
Primes
|
|
3
|
1030
|
Paul Leyland
|
1994
|
1997
|
-
|
88
|
|
1031
|
1050
|
Paul Leyland
|
2001-Jun-4
|
2001-Jun-4
|
-
|
4
|
|
1051
|
1500
|
Andrey Kulsha
|
2001-Jun-3
|
2001-Jun-23
|
-
|
41
|
|
1501
|
1700
|
Paul Leyland
|
2001-Jun-5
|
2001-Jun-11
|
-
|
18
|
|
1701
|
2000
|
Christ van Willegen
|
2001-Jun-5
|
2001-Jun-9
|
-
|
23
|
|
2001
|
2200
|
Greg Childers
|
2001-Jun-7
|
2001-Jun-9
|
-
|
19
|
|
2201
|
2400
|
Greg Childers
|
2001-Jun-9
|
2001-Jun-12
|
11
|
6
|
|
2401
|
2600
|
Peter Liaskovsky
|
2001-Aug-31
|
2001-Sep-3
|
17
|
5
|
|
2601
|
2700
|
Paul Leyland
|
2001-Jul-24
|
2001-Aug-8
|
9
|
4
|
|
2701
|
2800
|
Greg Childers
|
2001-Jul-30
|
2001-Jul-31
|
5
|
2
|
|
2801
|
3000
|
Greg Childers
|
2001-Jul-31
|
2001-Aug-5
|
12
|
2
|
|
3001
|
3050
|
Sander Hoogendoorn
|
2001-Jun-14
|
2001-Jun-19
|
2
|
-
|
|
3051
|
3100
|
Peter Liaskovsky
|
2001-Sep-3
|
2001-Sep-5
|
4
|
2
|
|
3101
|
3200
|
Alexander Kuzmich
|
2001-Sep-16
|
2001-Oct-6
|
12
|
-
|
|
3201
|
3379
|
Leonid Muraviov
|
2001-Nov-28
|
2002-Mar-28
|
11
|
1
|
|
3380
|
3500
|
Andrey Kulsha
|
2002-Apr-19
|
2002-May-19
|
7
|
-
|
|
3501
|
4400
|
Paul Leyland
|
2001-Dec-21
|
2002-Jun-27
|
66
|
3
|
|
4401
|
4500
|
Greg Childers
|
2002-Jul-13
|
2002-Aug-13
|
8
|
1
|
|
4501
|
5000
|
Mark Rodenkirch
|
2002-Sep-7
|
2002-Nov-19
|
42
|
-
|
|
5001
|
5100
|
Paul Leyland
|
2003-Jun-13
|
2003-Jun-23
|
10
|
1
|
|
5101
|
5200
|
Paul Leyland
|
2003-Jun-23
|
2003-Jul-6
|
5
|
-
|
|
5201
|
5500
|
Greg Childers
|
2003-Jul-21
|
2003-Sep-17
|
17
|
-
|
|
5501
|
7500
|
Anatoly Selevich
|
2003-Jun-25
|
2004-Aug-7
|
152
|
2
|
|
7501
|
10000
|
Anatoly Selevich
|
2007-Feb-27
|
2008-Apr-1
|
174
|
-
|
|
10001
|
12000
|
Anatoly Selevich
|
2008-Jun-24
|
2010-May-22
|
133
|
2
|
|
12001
|
12050
|
Jens Kruse Andersen
|
2008-Dec-27
|
2009-Jan-8
|
3
|
-
|
|
12051
|
40000
|
Available for y > 1000
|
-
|
-
|
47
|
2
|
|
40001
|
500000
|
Available for y > 10
|
-
|
-
|
12
|
-
|
|
500001
|
infinity
|
Available
|
-
|
-
|
-
|
-
|
So far, 226 primes and 759 probable primes were found.
The range 20000 < x < 40000 for y <
1000 is being searched by Serge Batalov and Andrey Kulsha;
the higher x's for y < 10 are being searched
by Anatoly Selevich.
All the ranges up to x = 3500 inclusively were double-checked
by Andrey Kulsha; the range up to x = 4000 was checked by Göran Hemdal. |