A202222 Number of permutations avoiding the consecutive pattern 23451.

1, 2, 6, 24, 119, 708, 4914, 38976, 347795, 3448312, 37608186, 447452544, 5767315785, 80054392880, 1190583423414, 18887010379776, 318343175603145, 5681348801115680, 107025793890636390, 2122275973981599744, 44188021441868910375, 963852638874607648320

Offset

1,2

Comments

a(n) is the number of permutations on [n] that avoid the consecutive pattern 23451. It is the same as the number of permutations which avoid 13452, 25431, 41235, 53214, 13542, 24531, 42135, 53124, 14352, 25341, 41325, 52314, 14532, 23541, 43125, 52134, 15342, 24351, 42315, 51324, 15432, 43215 or 51234.

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: A202216 A202217 A202221 * A202214 A202215 A202218

Adjacent sequences: A202219 A202220 A202221 * A202223 A202224 A202225

Keyword

nonn

Author

Ray Chandler, Dec 15 2011

Status

approved