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A284718
Number of indecomposable permutations avoiding the pattern 1324.
1
1, 1, 1, 3, 13, 69, 396, 2355, 14363, 89706, 573828, 3758866, 25195016, 172591294, 1206482317, 8592827996, 62257890162, 458214977642, 3421294482237, 25884913987768, 198236423171483, 1535315006313002, 12015208271571543, 94943908405295171, 757044806198966152
OFFSET
0,4
LINKS
Bjarki Ágúst Guðmundsson, Table of n, a(n) for n = 0..50 (terms 25..50 by Bjarki Ágúst Guðmundsson, computed using Kotesovec's formula and terms from the Conway/Guttmann/Zinn-Justin reference)
Andrew R. Conway, Anthony J. Guttmann and Paul Zinn-Justin, 1324-avoiding permutations revisited, arXiv preprint arXiv:1709.01248 [math.CO], 2017.
A. L. L. Gao, S. Kitaev, P. B. Zhang. On pattern avoiding indecomposable permutations, arXiv:1605.05490 [math.CO], 2016.
FORMULA
For n>1, a(n) = A061552(n) + 3*A000108(n) - A000108(n+1) - 2*A000108(n-1). - Vaclav Kotesovec, Apr 02 2017
CROSSREFS
Cf. A061552.
Sequence in context: A121954 A058307 A020107 * A284719 A128079 A074534
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 02 2017
EXTENSIONS
More terms from Vaclav Kotesovec, Apr 02 2017
a(0) prepended by Bjarki Ágúst Guðmundsson, Dec 18 2017
STATUS
approved