The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A198434 Number of simple symmetric permutations of degree 2n (or 2n+1). 0
 2, 10, 90, 966, 12338, 181470, 3018082, 55995486, 1146939010, 25716746430, 626755197698, 16502357651966, 466944932413442, 14133259249586174, 455715081098876418, 15596665064842012158, 564724372634695925762, 21568978799171323200510, 866674159679235417061378, 36548294282449538711357438 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS A permutation is simple if the only intervals that are fixed are the singletons and [1..m]. A permutation p is symmetric if i+j=m+1 implies p(i)+p(j)=m+1. For example the permutations 1234  and   12345 2413        25314 are both simple and symmetric. Symmetric simple permutations of degree 2n+1 correspond to simple permutations in the Weyl group of type B_n. Symmetric simple permutations of degree 2n correspond to simple permutations in the Weyl group of type C_n. These occur in pairs so all entries in this sequence will be even. LINKS R. Dewji, I. Dimitrov, A. McCabe, M. Roth, D. Wehlau and J. Wilson, Decomposing Inversion Sets of Permutations and Applications to Faces of the Littlewood-Richardson Cone, arXiv:1110.5880v1[math.CO] EXAMPLE The simple symmetric permutations of lowest degree are 2413, 3142, 25314, 41325. CROSSREFS Cf. A111111. Sequence in context: A326554 A055779 A338050 * A326089 A277403 A179423 Adjacent sequences:  A198431 A198432 A198433 * A198435 A198436 A198437 KEYWORD nonn AUTHOR David Wehlau, Oct 24 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 16 12:38 EDT 2021. Contains 343947 sequences. (Running on oeis4.)