A202231 Number of permutations avoiding the consecutive pattern 45123.

1, 2, 6, 24, 119, 708, 4914, 38980, 347862, 3449292, 37622348, 447662376, 5770553184, 80106726784, 1191471740436, 18902847341664, 318639524995160, 5687162644422552, 107145206713313556, 2124840033683212648, 44245492380155416392, 965195327390976439656

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 45123. It is the same as the number of permutations which avoid 21543, 32154 or 34512.

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.