[seqfan] Re: no square
Rob Pratt
Rob.Pratt at sas.com
Mon May 16 23:56:17 CEST 2016
http://oeis.org/A240443
-----Original Message-----
From: SeqFan [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of hv at crypt.org
Sent: Monday, May 16, 2016 4:29 PM
To: seqfan at list.seqfan.eu
Subject: [seqfan] no square
A variant of both A271906 and A227133: Size of the largest subset S of the points of an n X n square grid such that no four of the points of S form a square.
For n x n it looks rather simple (for the values I've managed to calculate):
1 3 6 10 15
.. but the full m x n results are not in OEIS, and may hint at more
complexity:
1 2 3 4 5 6 7 8
2 3 5 6 8 9 11 12
3 5 6 8 10 12 14 16
4 6 8 10 13 15 18 20
5 8 10 13 15 19
6 9 12 15 19
7 11 14 18
8 12 16 20
I need to rewrite my code to get more results, I want to get at least up to 8 x 8.
More generally, should all sequences relating to "an n x n grid" be under consideration for extending to "an m x n grid"? I appreciate a few will make no sense, but it seems like in most cases it should be a natural extension - I was surprised not to see it for the recently discussed right-triangles case.
Hugo
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