[seqfan] A005646(11)=5236990, and triangle now linked to A039754

[Robert Munafo]

The A005646 "triangle" (which I am calling with my reserved A-number
A171871) can be seen at mrob.com/pub/math/seq-a005646.html#triangle

Thanks to analytical work by Andrew Weimholt we determined that the term
just above the 1's at the bottom of each column is A034198, which led me to
the paper at http://www.uni-graz.at/~fripert/blockcodes.html<http://www.uni-graz.at/%7Efripert/blockcodes.html>

In Table 1 on page 3 we find:

1 1 1 1 1
1 1 1 1 1
1 2 3 4 5
.. 1 3 6 10
.. 1 6 19 47
.. .. 3 27 131
.. .. 3 50 472
.. .. 1 56 1326
.. .. 1 74 3779
(etc.)

which has many of the same numbers (reading down from the top) as the
A171871 triangle reading up from the bottom. In the Nth column the first
2^(N-1) terms agree.

Also, A005646(11)=5236990, and the whole N=11 row has been enumerated. The
next row would likely take a few months with the current approach, so I'm
not going to bother.

But between Andrew and I, we have added 4 terms to a "nice,more" sequence
that hasn't changed since 1979, and that's pretty good (-:

-- 
 Robert Munafo  --  mrob.com