Various items, Dec 20 2006

[N. J. A. Sloane]

1. The "vacation" policy sometimes fails, when there are a lot of emails
about a sequence that is not yet in the OEIS.  So I am adding this:

%I A124129
%S A124129 3,7,13,23,31,113
%N A124129 Primes p for which there are no primes between p and p+sqrt(p).
...
%A A124129 Remi Eismann (reismann(AT)free.fr), Dec 10 2006

This way I can clean up a lot of emails.  In future, once a sequence
is the subject of more than a couple of messages, it should be sent
in the OEIS right away, so that it gets an A-number.

2.  The purpose of the "vacation" was to cut down on the junk submissions,
to enable me to get caught up with emails, and so that I can work on
some other urgent things.  This is working, sort-of, and I will
probably extend the "vacation" until the end of January.

3.  Someone asked me about 4 puzzle sequences that he heard when he was
in hospital.  They are:
1B1, ?, 1B2, ?,1B3, D, 1B4, C   [he says he solved that one but did not tell me his answer]
12, ?, 33, 44, 44
72, ?, 96, ?, 89, ?, 103, 91, 72
29, ?, 25, ?, 16, ?, 13, 60, 13, 57

Can anyone solve them?  I don't know the answers.

4.  An interesting recent entry:
%I A124104
%S A124104 0,2,36,600,11100,235560,5746524
%N A124104 Sum of the Rand distance between all pairs of set partitions of {1, 2, ... n}.
%D A124104 W. Rand, Objective criteria for the evaluation of clustering methods. J. Amer. Stat. Assoc., 66 (336): 846-850, 1971.
%e A124104 E.g. a(2) = 2 = 1 + 1 + 0 + 0 because the distance from 1,2 to 12 is 1 (and vice versa) and the distance from 1,2 to 1,2 or 12 to 12 is 0.
%K A124104 hard,nonn,new
%O A124104 1,2
%A A124104 Andrey Goder (andy.goder(AT)gmail.com), Dec 12 2006

- what is the Rand distance?


5. I still have several hundred "Comments" to process. Also a huge number
of emails, new submissions, etc.

6. Thanks to everyone who has sent in b-files (especially Tony Noe, David Wasserman,
Zak Seidov).  There are now nearly 2000 entries with b-files.

7. Best wishes for 2007 to everyone!

Neil