Flat Maze sequence
Eric Angelini
keynews.tv at skynet.be
Thu Mar 3 11:51:34 CET 2005
Hello math-fun and SeqFan,
I don't know if this is old hat -- if yes please ignore.
Rules for a new arrangement of the natural integers :
0) At the beginning there was a (semi)-infinite row of
empty labels;
1) Then came the Pencil who wrote "1" on the first (most-
left) one;
2) "1" meant: "write now whatever integer you want (but
not used so far) on the label to the right of me at a
distance of "1" step;
[and, more generally, an odd integers means: "go 2k+1
labels to the right and write smthg new on it -- the
label must be blank, though". An even integers means:
"go 2k labels to the left and write...".]
Question: is there an algorithm to rearrange all the na-
tural integers with those two simple rules (leaving no
empty labels behind) ?
I have started this possible sequence (a dot means "still
empty label"; the next label to be named has an "x"):
1 3 5 7 2 11 15 4 17 13
9 6 21 23 25 27 10 . . 8
. 12 14 . 17 19 . . . .
. . . 20 . . 22 . . 24
. x 18 . 32 . . . . .
This sequence looks like an "flat maze" -- thus the name.
The above has been done by hand -- this explains why the
rows are 10 integers long: labels are easier to reach be-
cause a vertical step (downwards) adds 10 to the count.
Best,
É.
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