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

Author

Ray Chandler, Dec 15 2011

Keywords

• nonn

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.