OFFSET
1,3
COMMENTS
LINKS
EXAMPLE
For n = 7 foldings (1 6 5 4 3 2 7), (4 5 6 1 7 2 3), (3 4 5 6 1 7 2), and (1 7 2 3 4 5 6) cannot be produced if stamps are sticky on both sides and we are only allowed to do complete folds. If stamps are not sticky and we are still only allowed to do complete folds, these foldings are still possible. For example, folding strategy for (1 6 5 4 3 2 7):
Unfolded:
<1--2--3--4--5--6--7>
Step 1:
/-3--4--5--6--7>
\-2--1>
Step 2:
<7--6--5--4-\
/-3-/
\-2--1>
Step 3:
<7--6-\
/-5-/
\-4-\
/-3-/
\-2--1>
Step 4:
/---6-\
| /-5-/
| \-4-\
| /-3-/
| \-2--1>
\---7>
Step 5:
<1---\
/---6-\ |
| /-5-/ |
| \-4-\ |
| /-3-/ |
| \-2---/
\---7>
If stamps are sticky, this strategy fails, because after the first step stamps 1 and 4 cannot be separated (every other strategy also fails).
PROG
(Python) # See Link
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Klemen Klanjscek, Mar 29 2024
EXTENSIONS
a(15)-a(17) from Klemen Klanjscek, Jul 09 2024
STATUS
approved