A248900 Number of permutations of [n] avoiding patterns 2431 and 54321.

1, 1, 2, 6, 23, 102, 492, 2492, 13003, 69172, 372963, 2031174, 11148948, 61588814, 342068774, 1908740089, 10694374242, 60137305751, 339276548456, 1919787554118, 10892575241125, 61957028188350, 353224194632459, 2018076850631391, 11552829351121139, 66259093178740462

Offset

0,3

Links

Nathaniel Shar, Table of n, a(n) for n = 0..80

Nathaniel Shar, Maple code

Example

a(4) = 23 because all permutations of length 4 except 2431 lie in this set.

Crossrefs

Cf. A022558, A047889.

Sequence in context: A370196 A370213 A231444 * A120346 A050389 A098746

Adjacent sequences: A248897 A248898 A248899 * A248901 A248902 A248903

Keyword

nonn

Author

Nathaniel Shar, Mar 06 2015

Status

approved