[param.2.607] improved parameters to get a better yield
[param.2.607] improved parameters to get a better yield

On confit, build/f2/sieve param.2.607 q1=2001000 gives now:
645.232u 0.324s 10:48.04 99.6%  0+0k 0+0io 0pf+0w

Was before:
1015.403u 0.556s 16:59.74 99.6% 0+0k 0+0io 0pf+0w

mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs,mancoast/cado-nfs