A248900 - OEIS

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A248900

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

1

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

(list; graph; refs; listen; history; text; internal format)

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 * A376395 A120346 A050389

Adjacent sequences: A248897 A248898 A248899 * A248901 A248902 A248903

KEYWORD

nonn

AUTHOR

Nathaniel Shar, Mar 06 2015

STATUS

approved