Try f_2=1.260997000000 k p_k f_k time ln k+lnln k-(f_k/k)^.5 2 3 1.260997 0 -0.467405 3 5 3.00788726543 0 0.191346 4 7 5.86093616488 0 0.502460 5 11 9.03207826012 0 0.741293 6 13 13.3034371748 0 0.885918 7 17 17.9968693037 0 1.008212 8 19 23.9097203956 0 1.082751 9 23 30.3872024218 0 1.146933 10 29 36.7236984479 0 1.220275 21 73 138.877079812 0 1.586253 100 541 1691.36119643 0 2.019734 1000 7919 42420.1943523 0 2.327321 10000 104729 802070.328172 0 2.474829 51000 625187 5820352.04126 0 2.539876 100000 1299709 12982769.6023 0 2.562200 1000000 15485863 190542531.476 0 2.637588 10000000 179424673 2582959035.71 2 2.826451 Succeeded at k=21381000, p=400885651 5 seconds Try f_2=1.260997375000 k p_k f_k time ln k+lnln k-(f_k/k)^.5 2 3 1.260997375 0 -0.467405 3 5 3.00788829491 0 0.191346 4 7 5.86093846316 0 0.502460 5 11 9.03208215279 0 0.741293 6 13 13.3034434829 0 0.885917 7 17 17.9968785286 0 1.008212 8 19 23.9097336708 0 1.082750 9 23 30.3872205162 0 1.146933 10 29 36.7237215536 0 1.220274 21 73 138.87721517 0 1.586252 100 541 1691.36577667 0 2.019728 1000 7919 42420.7843378 0 2.327276 10000 104729 802133.77222 0 2.474475 51000 625187 5821999.05463 0 2.538365 100000 1299709 12989046.9042 0 2.559446 1000000 15485863 191137675.865 0 2.616047 10000000 179424673 2637430663.15 2 2.657870 100000000 2038074743 34752192543.7 24 2.692215 1000000000 22801763489 441872868631 276 2.733751 10000000000 252097800623 5.42093223619e+012 3250 2.879573 Succeeded at k=19269602000, p=498961938779 6523 seconds