|
%I #35 Oct 20 2017 14:25:35
%S 1,1,2,5,16,60,260,1260,6744,39303
%N Number of equivalence classes of S_n under transformations of positionally adjacent elements of the form abc <--> cba where a<b<c.
%H Steven Linton, James Propp, Tom Roby, and Julian West, <a href="http://arxiv.org/abs/1111.3920"> Equivalence classes of permutations under various relations generated by constrained transpositions, 2011</a> arXiv:1111.3920 [math.CO], <a href="https://cs.uwaterloo.ca/journals/JIS/VOL15/Roby/roby4.html">J. Int. Seq. 15 (2012) #12.9.1</a>
%e From _Alois P. Heinz_, May 16 2012: (Start)
%e a(3) = 5: {123, 321}, {132}, {213}, {231}, {312}.
%e a(4) = 16: {1234, 1432, 3214}, {1243, 4213}, {1324}, {1342, 4312}, {1423}, {2134, 2431}, {2143}, {2314}, {2341, 4123, 4321}, {2413}, {3124, 3421}, {3142}, {3241}, {3412}, {4132}, {4231}. (End)
%Y Cf. A210667, A210669, A210671, A212417.
%K nonn
%O 0,3
%A _Tom Roby_, May 08 2012
%E Definition improved by _Tom Roby_, May 15 2012
%E a(0)-a(2), a(9) from _Alois P. Heinz_, May 16 2012
|
