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Number of solvable clock puzzles with n positions in Final Fantasy XIII-2.
2

%I #12 Apr 28 2021 14:14:19

%S 0,1,1,13,32,507,1998,33136,193995,3426518,27187715,501668052,

%T 5124675822

%N Number of solvable clock puzzles with n positions in Final Fantasy XIII-2.

%C The sequence gives the number of ways of placing the integers 1, 2, ..., floor(n/2) (with repetition) in n spaces on a circle so that you can jump to every integer exactly once, and the distance you jump is equal to the integer you are currently standing on.

%C A206344 is a trivial upper bound.

%C This is the same as A206346, except clock puzzles that are rotations or reflections of each other are counted as distinct.

%H N. Johnston, <a href="http://www.njohnston.ca/2012/02/counting-and-solving-final-fantasy-xiii-2s-clock-puzzles/">Counting and Solving Final Fantasy XIII-2's Clock Puzzles</a>

%e A solvable clock puzzle in the n = 6 case arises from the following integers (placed clockwise around a circle): 1, 3, 3, 2, 1, 3. If we label the positions 0, 1, 2, 3, 4, 5, then a solution to this puzzle is the following sequence of positions: 0, 1, 4, 3, 5, 2.

%Y Cf. A206344, A206346.

%K nonn,more

%O 1,4

%A _Nathaniel Johnston_, Feb 06 2012

%E a(10) from _Nathaniel Johnston_, Feb 07 2012

%E a(11)-a(13) from _Bert Dobbelaere_, Apr 28 2021