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A212581 Number of equivalence classes of S_n under transformations of positionally and numerically adjacent elements of the form abc <--> acb <--> bac where a<b<c. 3
1, 1, 2, 4, 17, 89, 556, 4011, 32843, 301210 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..9.

S. Linton, J. Propp, T. Roby, and J. West, Equivalence classes of permutations under various relations generated by constrained transpositions, 2011 arXiv:1111.3920 [math.CO] J. Int. Seq. 15 (2012) #12.9.1

EXAMPLE

From Alois P. Heinz, May 22 2012: (Start)

a(3) = 4: {123, 132, 213}, {231}, {312}, {321}.

a(4) = 17: {1234, 1243, 1324, 2134}, {1342}, {1423}, {1432}, {2143}, {2314}, {2341, 2431, 3241}, {2413}, {3124}, {3142}, {3214}, {3412}, {3421}, {4123, 4132, 4213}, {4231}, {4312}, {4321}. (End)

CROSSREFS

Cf. A210667, A210668, A210669, A210671, A212417, A212580.

Sequence in context: A014522 A020035 A112005 * A305786 A009319 A009323

Adjacent sequences:  A212578 A212579 A212580 * A212582 A212583 A212584

KEYWORD

nonn,hard,more

AUTHOR

Tom Roby, May 21 2012

EXTENSIONS

a(9) from Alois P. Heinz, May 22 2012

STATUS

approved

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Last modified March 18 13:47 EDT 2019. Contains 321289 sequences. (Running on oeis4.)