
COMMENTS

a(n) is the number of (changeringing) sequences of length[*] n when we are looking at sequences of permutations of the set {1,2,3,4,5,6,7,8,9} that satisfy:
1. The position of each bell (number) from one permutation to the next can stay the same or move by at most one place.
2. No permutation can be repeated except for the starting permutation which can be repeated at most once at the end of the sequence to accommodate criterion 4.
3. The sequence must start with the permutation (1,2,3,4,5,6,7,8,9).
And does not satisfy:
4. The sequence must end with the same permutation that it started with.
[*]: We define the length of a changeringing sequence to be the number of permutations in the sequence.
With this [*] definition of the length of a changeringing sequence; for 9 bells we get a maximum length of factorial(9)=362880, thus we have 362880 possible lengths, namely 1,2,...,362880. Hence {a(n)} has 362880 terms. For m bells, where m is a natural number larger than zero, we get a maximum length of factorial(m). When denoting the number of path changeringing sequences of length n for m bells as a_m(n), {a_m(n)} has factorial(m) terms for all m.


CROSSREFS

4 bells: A324942, A324943.
5 bells: A324944, A324945.
6 bells: A324946, A324947.
7 bells: A324948, A324949.
8 bells: A324950, A324951.
9 bells: A324952, This sequence.
Number of allowable transition rules: A000071.
Sequence in context: A262112 A076009 A003755 * A174445 A206940 A188612
Adjacent sequences: A324950 A324951 A324952 * A324954 A324955 A324956
