Awesome find. Many thanks to Phil for his prime finding software.
Although I no longer use overseis, I do use phrot extensively and am
using it in the hopes of finding another megabit prime as part of the
GCW13 mini-project over at PrimeGrid.

--Mark

On Apr 5, 2009, at 9:43 AM, Bob Hillegas wrote:

> 9152_k2_750000-800000_2of2.abc
> (4925/9034 54%) Running 22620:00 minutes
> 4887:Phi(49152,1242871618688) b=(2*1)*788312^2 (658257bits)
> res=(-1+0w) at
> bit 17. maxerr=0.119125. Time=1405.310 => is 2-SPRP.
>
> Got ONE!!
> /usr/local/bin/overseis.p4 -t -q 49152 1242871618688
> OversEis version:0.92F Weighting:0.2o/c=s+r/s=r/l=sB/^2 Transform:DJB
> +PC
> Phi(49152,1242871618688) Form Phi(2^14*3^1,b) uses 16384 type-1 limbs
> (size="14")
> : base 1242871618688 has 3 factors.
> 11^((p-1)/28154) = 655360 651264 647168 643072 638976
> 634880 630784 626688 622592 618496 614400
> 610304 606208 602112 598016 593920 589824
> 585728 581632 577536 573440 569344 565248
> 561152 557056 552960 548864 544768 540672
> 536576 532480 528384 524288 520192 516096
> 512000 507904 503808 499712 495616 491520
> 487424 483328 479232 475136 471040 466944
> 462848 458752 454656 450560 446464 442368
> 438272 434176 430080 425984 421888 417792
> 413696 409600 405504 401408 397312 393216
> 389120 385024 380928 376832 372736 368640
> 364544 360448 356352 352256 348160 344064
> 339968 335872 331776 327680
> 323584 319488 315392 311296 307200 303104
> 299008 294912 290816 286720 282624 278528
> 274432 270336 266240 262144 258048 253952
> 249856 245760 241664 237568 233472 229376
> 225280 221184 217088 212992 208896 204800
> 200704 196608 192512 188416 184320 180224
> 176128 172032 167936 163840 159744 155648
> 151552 147456 143360 139264 135168 131072
> 126976 122880 118784 114688 110592 106496
> 102400 098304 094208 090112 086016 081920
> 077824 073728 069632 065536 061440 057344
> 053248 049152 045056 040960 036864 032768
> 028672 024576 020480 016384 012288 008192
> 004096 000000 (-69230768229+492886883205w)
> , maxerr=0.120255. not '1', good.
> 11^(p-1) = (1+0w), maxerr=0.120255 => is Fermat 11-PRP.
> 11^(p-1)/2 :(-1+0w), maxerr=0.083603 => 128^8192 divides order, 8.71%
> 11^(p-1)/7 :(356004841550+-517771633455w), maxerr=0.078735 =>
> 2401^8192
> divides order, 13.98%
> 11^(p-1)/2011 :(-204788373302+-326014581962w), maxerr=0.073483 =>
> 4044121^8192 divides order, 27.31%
> 50.00% attained for Pocklington (contingent on maxerr=0.120255)
> Time=1868.660 => is prime.
>
> --
> BobH



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