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URL: https://oeis.org/A230552

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A230552
Number of involutions avoiding the pattern 2341.
5
1, 2, 4, 10, 25, 66, 170, 441, 1124, 2870, 7273, 18477, 46825, 118917, 301734, 766525, 1946293, 4944614, 12557685
OFFSET
1,2
LINKS
Miklós Bóna, Cheyne Homberger, Jay Pantone, and Vince Vatter, Pattern-avoiding involutions: exact and asymptotic enumeration, arxiv:1310.7003 [math.CO], 2013-2014.
EXAMPLE
Of the 26 involutions of length 5, only 52341 contains the pattern 2341, so a(5) = 25.
KEYWORD
nonn,more
AUTHOR
Cheyne Homberger, Oct 23 2013
STATUS
approved