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A284713
Number of indecomposable permutations avoiding the pattern 4231.
1
1, 1, 3, 12, 56, 289, 1604, 9415, 57801, 368269, 2421115, 16352401, 113075441, 798316997, 5741446395, 41984708298, 311673028845, 2345644392051, 17876342623580, 137820598360123, 1073961913716521, 8452182814380104, 67136452766364121, 537890721293399309
OFFSET
1,3
LINKS
A. L. L. Gao, S. Kitaev, P. B. Zhang. On pattern avoiding indecomposable permutations, arXiv:1605.05490 [math.CO], 2016.
FORMULA
G.f.: 1 - 1/g(x), where g(x) is the (at present unknown) g.f. for A061552. - Vaclav Kotesovec, Apr 03 2017
CROSSREFS
Cf. A061552.
Sequence in context: A303925 A215252 A284712 * A180256 A369600 A027390
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 02 2017
EXTENSIONS
More terms from Vaclav Kotesovec, Apr 03 2017
Name corrected by Michael D. Weiner, Apr 10 2018
STATUS
approved