[seqfan] Re: Correcting A002932 (n-step walks on square lattice)

N. J. A. Sloane njas at research.att.com
Mon Nov 22 15:47:55 CET 2010

>Date: Mon, 22 Nov 2010 13:24:38 +0000 (UTC)
>From: "Joseph S. Myers" <jsm at polyomino.org.uk>
>Subject: [seqfan]  Correcting A002932 (n-step walks on square lattice)

>A002932 is "Number of n-step walks on square lattice." - where there is a 
>restriction (see the Fisher and Hiley reference) that no lattice point 
>appears more than once in the path, and no two points in the path that are 
>not consecutive in the path may be adjacent in the lattice.

>There are two entries in the "formula" section both of which are wrong - 
>one reporting an observed link to A001333 and the other giving an explicit 
>formula; they go wrong from the term with value 940 onwards, where both 
>give the value 956 instead.  (They would probably be correct if the 
>adjacency restriction was local, only relating to points 3 apart in the 
>path, though I haven't checked this.)

>The last term given of the sequence, 396204, disagrees with my 
>calculations; I get 396172 although my program agrees with the earlier 
>terms.  Before I make corrections (and extensions - I have eight more 
>terms) to this sequence, could someone confirm whether they get the figure 
>I do or the figure in the sequence (which is accurately transcribed from 
>the Fisher and Hiley reference)?

>Joseph S. Myers
>jsm at polyomino.org.uk

Joseph, I think the best thing to do is for you to
submit your version as a new entry, and then to add a comment
to A002932 saying that this is probably an erroneous version of

Also the two incorrect formulas in A002932 should be deleted - could you please do that?



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