[seqfan] Walks
franktaw at netscape.net
franktaw at netscape.net
Thu Mar 10 04:38:29 CET 2011
I just submitted a sequence https://oeis.org/draft/A187430 (Number of
non-negative walks of length n with step sizes 1 and 2, starting and
ending at 0.)
If one takes such walks without the restriction that it end at 0, then
one can get T(n,k) to be the number of such walks ending at k. This
starts:
1
0,1,1
2,1,1,2,1
2,5,6,3,3,3,1
11,11,13,17,13,7,6,4,1
24,41,52,44,43,40,25,14,10,5,1
The row sums of this sequence, which is the total number of walks of
this sort of length n, starts
1,2,7,23,83,299,1107,4122,15523
This appears to be left-shifted A047002, array T(n,n) where T(n,k) =
A047000(n,k) is the number of paths consisting of steps from (0,0) to
(h,k) such that each step has length 1 directed up or right and no step
touches the line y=x/2 unless x=0 or x=h.
This is not obvious to me. Can anyone verify it?
Franklin T. Adams-Watters
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