A202216 Number of permutations avoiding the consecutive pattern 34521.

1, 2, 6, 24, 119, 708, 4914, 38976, 347775, 3447912, 37601586, 447346944, 5765604885, 80025786960, 1190085736014, 18877969022976, 318171464604945, 5677939605422880, 106955077375109430, 2120744934976978944, 44153462828412744975, 963040357207773472320

Offset

1,2

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 34521. It is the same as the number of permutations which avoid 12453, 31245, 35421, 54213, 12543, 32145 or 54123.

Links

Ray Chandler, Table of n, a(n) for n = 1..40

A. Baxter, B. Nakamura, and D. Zeilberger. Automatic generation of theorems and proofs on enumerating consecutive Wilf-classes

Crossrefs

Cf. A177523, A202213-A202236.

Sequence in context: A297200 A071077 A202213 * A202217 A202221 A202222

Adjacent sequences: A202213 A202214 A202215 * A202217 A202218 A202219

Keyword

nonn

Author

Ray Chandler, Dec 14 2011

Status

approved