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%I #27 Mar 06 2015 11:28:04
%S 1,1,2,6,23,102,492,2492,13003,69172,372963,2031174,11148948,61588814,
%T 342068774,1908740089,10694374242,60137305751,339276548456,
%U 1919787554118,10892575241125,61957028188350,353224194632459,2018076850631391,11552829351121139,66259093178740462
%N Number of permutations of [n] avoiding patterns 2431 and 54321.
%H Nathaniel Shar, <a href="/A248900/b248900.txt">Table of n, a(n) for n = 0..80</a>
%H Nathaniel Shar, <a href="/A248900/a248900.txt">Maple code</a>
%e a(4) = 23 because all permutations of length 4 except 2431 lie in this set.
%Y Cf. A022558, A047889.
%K nonn
%O 0,3
%A _Nathaniel Shar_, Mar 06 2015
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