login
A060135
Sequence of adjacent transpositions (a[n] a[n]+1), which, when starting from the identity permutation and applied successively, produce a Hamiltonian circuit through all permutations of S_4, in such a way that S_{n-1} is always traversed before the rest of S_n. Furthermore, each subsequence from the first to the (n!-1)-th term is palindromic.
2
1, 2, 1, 2, 1, 3, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 3, 1, 2, 1, 2, 1
OFFSET
0,2
COMMENTS
This is lexicographically the ninth of all such Hamiltonian paths through S4.
I will try to extend this in some elegant fashion through all S_inf so that the same criteria will hold. There are 466 ways to extend this to S5.
FORMULA
[seq(sol9seq(n), n=1..23)];
MAPLE
sol9seq := n -> (`if`((n < 13), adj_tp_seq(n), sol9seq(24-n)));
CROSSREFS
Cf. A057112.
Sequence in context: A333940 A292997 A372471 * A057112 A071956 A077767
KEYWORD
nonn
AUTHOR
Antti Karttunen, Mar 02 2001
STATUS
approved