1aorpo

Three seeds reproduce all seven posts, and they sit in the most likely boot window, where about 1.25 chance matches would be expected. Nothing separates them firmly, so the run is not counted as reproduced.

Why it is hard

Each post has eight possible values, so the seven posts carry 21 bits: a random seed matches them by chance about once in 2 million. Over all seeds that is about a thousand chance matches. The first post is on a round schedule time, so the launch can be anywhere in the 132 minutes (1.1 posting intervals) before it. Even with the boot known to the second, that window alone holds about 0.2 chance matches.

How it was narrowed

Step	Constraint	Candidates	Expected by chance	Seeds found
Every seed	First post at draw 1 (2013 build)	about 137 million	65	68 on the tick grid
Run 42's boot	A fresh start on the 13 February boot	about 770,000	0.37	0, so not that boot
After run 42	A boot after its last post (9 March, 01:26:46), launch within 132 minutes	about 65 million	31	33
Patch-Tuesday reboot	A boot on 13 March, 09:00 to 12:30 UTC	about 1.3 million	0.63	2
Patch-Tuesday reboot	A boot on 13 or 14 March, 09:00 to 12:30 UTC	about 2.6 million	1.25	3

The reboot is a reasonable guess. Of about 28 distinct boots in the run table from 2013 on, 16 fall one or two days after Patch Tuesday, at about 09:30 to 12:30 UTC. March 2013's Patch Tuesday was 12 March, and the daylight-saving change had already happened, so 03:00 Pacific is 10:00 UTC. The last post was at 09:00 UTC on 21 March. The next slot, at 11:01, would have fallen after the machine's reboot at about 09:35 to 10:19 that morning. That is the same pattern as the other short pieces: the run stops when the machine reboots.

The candidates

Seed	Startup draw (never posted)	Draws 1 to 7	Boot (UTC)	Fits the reboot
643,201,468	52	44, 40, 56, 56, 52, 48, 56	13 March, 08:08 to 10:20	yes: 01:08 to 03:20 Pacific
636,247,656	40	44, 40, 56, 56, 52, 48, 56	13 March, 10:04 to 12:16	yes: 03:04 to 05:16 Pacific
542,563,171	56	44, 40, 56, 56, 52, 48, 56	14 March, 12:06 to 14:18	at the edge: 05:06 to 07:18 Pacific

All three reproduce draws 1 to 7 against the stream of the .NET generator. The launch for any of them is between 18:49 and 21:01 UTC on 20 March (a Wednesday, 11:49 to 14:01 Pacific), within the hours the operator usually started runs in, so the launch time does not decide between them.

Reading. If the true seed is in the window, one true match plus about 1.25 chance matches predicts three hits well, but chance alone gives three or more about one time in eight. The two seeds from 13 March are the likely pair. 542,563,171 is weaker, since its boot is later than the usual reboot hour.

Chance matches cluster

Seeds a fixed distance apart share their first draws in the .NET generator, so chance matches come in clusters. Allowing for that, the empirical probability of three or more matches in the 13 and 14 March window is about 0.17, not the 0.13 a simple count gives.

What has been ruled out

• The GUID-list seeds in the post bodies are wall-clock milliseconds, not uptime, so they cannot date the boot.
• The launch hour is the same for all three candidates.
• The startup draw has no visible use. Its value gives only a weak hint: 643,201,468 falls in a band where such draws have been slightly more common across the 2013 runs. That is an after-the-fact pattern, and it does not decide the choice.

What could decide it

An independent constraint on the 13 March boot, or on the launch time to within about 30 minutes, or a second piece that ran on the same boot.