FYI, I've got the next C181 in linear algebra now; ETA from this point is about 30 hours.

So what are you using? A quantum computer wouldn't need to do linear algebra (I was starting to wonder if you had one). It it a lot of conventional CPUs or special purpose hardware?

Chris (still slightly amazed at your throughput)

Just a lot of conventional CPUs...

(I am curious for my own edification as well: Why the interest in this particular Aliquot sequence? As opposed to, say, 276 -- the smallest of the open-ended sequences?)

The very small-seeded sequences (in particular 276) are and always were long-term reserved by people who have been in this field for years (decades? Paul Zimmermann). We can observe via the [URL="http://www.rechenkraft.net/aliquot/AllSeq.html"]AllSeq-database scraping tool[/URL] that work is indeed being done there. Perhaps slowly, but we must respect other people's reservations, right?

So (then unreserved) 4788 was chosen years ago by the forum and stayed dear to most participants' hearts. On top of that, there was once an exciting downride on it (and some of us had great fun riding that wave).

[QUOTE=ryanp;433169](I am curious for my own edification as well: Why the interest in this particular Aliquot sequence? As opposed to, say, 276 -- the smallest of the open-ended sequences?)[/QUOTE]

[QUOTE=Batalov;433171]The very small-seeded sequences (in particular 276) are and always were long-term reserved by people who have been in this field for years (decades? Paul Zimmermann). We can observe via the [URL="http://www.rechenkraft.net/aliquot/AllSeq.html"]AllSeq-database scraping tool[/URL] that work is indeed being done there. Perhaps slowly, but we must respect other people's reservations, right?

So (then unreserved) 4788 was chosen years ago by the forum and stayed dear to most participants' hearts. On top of that, there was once an exciting downride on it (and some of us had great fun riding that wave).[/QUOTE]In addition, 4788 is the "main" sequence start for 314718, which was, at one time, the longest sequence known. (Since eclipsed by [URL="http://factordb.com/sequences.php?se=1&aq=933436&action=last20"]933436[/URL].)

Aliquot sequence 3408 is also assigned to the forum though not [URL=http://www.mersenneforum.org/showthread.php?t=18421&page=23]much activity[/URL] has been done lately. It currently stands with a [URL=http://www.factordb.com/sequences.php?se=1&aq=3408&action=range&fr=1620&to=1620]C175[/URL].
Hint, hint.

The c181 is done now:

[CODE]Thu May 5 20:32:10 2016 prp71 factor: 16154997059017911740662227768113426012378939666568151702160749858675687
Thu May 5 20:32:10 2016 prp110 factor: 71778567619495893704430655892712998170338213837340401077450841986834864298530930586804110304930518105547880693[/CODE]

We'll see what we have next...

The c169 (8820260321...) for index 5260 is now in linear algebra; should be done by tomorrow morning.

c169 is factored:

[CODE]Sat May 7 01:22:26 2016 prp79 factor: 3844695644339670615607425287715145660859912603602727904626230373424319537548143
Sat May 7 01:22:26 2016 prp91 factor: 2294137465545832119813112814560093916957233303297810939424925504384223801170244092984755993[/CODE]

19 lines later and now the guide is 2^2, my second favorite :smile: