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  There are 1250 XYYXF composites from C154 to C321 by this time. Currently 8 of them are reserved; the remaining 1242 are available for your choice.

This chart arranges the composites on (x; y) plane and shows their distribution by x and by y:

Blinking squares mark reserved composites. The color depends on the decimal length of the composite; that's shown on this chart representing the distribution of the composites by their decimal length:

You see, there's a lot of work to do. It would be fine if you choose some of these squares and cause me to add a few lines to the table below.


Reserved composites
Composite
Contributor
When reserved
C177_109_106
David Metcalfe
April 7, 2013
C280_143_101
Sean Wellman
April 1, 2013
C280_143_112
Sean Wellman
April 1, 2013
C156_112_95
Bill Rea
March 31, 2013
C156_133_68
Bill Rea
March 31, 2013
C164_139_91
Sean Wellman
March 3, 2013
C176_137_49
Sean Wellman
October 18, 2012
C163_145_33
Sean Wellman
September 4, 2012

To choose the most efficient method of factorization and to avoid wasting CPU time, please take into account that all the composites passed P±1 tests with B1 from 100M to 4G and ECM tests up to B1 = 11M, and now are being tested with ECM at B1 = 43M by yoyo@home.

Some of the numbers survived deeper ECM tests; this table shows the amount of that additional work.

Additional ECM work

Composites
B1
# of cycles
C185_110_93
110M
18000
C205_110_97
110M
18000
C191_111_101
110M
18000
C200_111_110
110M
6706
C211_127_90
110M
18000
C244_129_82
110M
18000
C197_147_136
260M
6000
C305_142_139
850M
18000
C310_147_142
850M
18000
C311_148_133
850M
18000
C313_148_139
850M
18000
C316_149_132
850M
18000
C261_149_145
110M
18000
C321_149_146
850M
27000
C304_150_149
850M
18000

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Andrey Kulsha, Belarus