A260511 Number of signed permutations of length n that are sortable to the identity permutation by some sequence of cdr (context-directed reversal) moves.

1, 3, 15, 120, 1227, 15188

Offset

1,2

Links

Table of n, a(n) for n=1..6.

K. L. M. Adamyk, E. Holmes, G. R. Mayfield, D. J. Moritz, M. Scheepers, B. E. Tenner, and H. C. Wauck, Sorting permutations: games, genomes, and cycles, arXiv:1410.2353 [math.CO], 2014.

Example

a(2) = 3 because [1,2], [-1,2], and [1,-2] are sortable to the identity [1,2] using only context-directed reversal moves.

Crossrefs

A249165 gives the number of unsigned permutations sortable by context-directed swaps; this is the analog for signed permutations and context-directed reversals.

A260506 gives the number of signed permutations sortable by both cdr and cds moves together. This sequence is therefore always bounded by A260506.

A000165 counts the total number of signed permutations.

Sequence in context: A225115 A303353 A112228 * A093571 A093570 A107869

Adjacent sequences: A260508 A260509 A260510 * A260512 A260513 A260514

Keyword

nonn,more

Author

Caleb Stanford, Jul 27 2015

Status

approved