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A294825
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Number of permutations of [n] avoiding {2431, 1324, 1342}.
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0
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1, 1, 2, 6, 21, 77, 285, 1054, 3889, 14330, 52800, 194748, 719602, 2664989, 9894443, 36831886, 137465657, 514370974, 1929432068, 7254441076, 27336758102, 103229845714, 390594944522, 1480679644876, 5622915464986, 21388666960212, 81486623660720, 310907347188280, 1187905972634884
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OFFSET
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0,3
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LINKS
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Table of n, a(n) for n=0..28.
D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 [math.CO] (2017), Table 1 No 213.
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MAPLE
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C := (1-sqrt(1-4*x))/2/x ;
((1 -5*x +8*x^2 -5*x^3)*C -1 +4*x -4*x^2 +x^3)/(x^2*(1 -2*x)) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;
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CROSSREFS
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Sequence in context: A294822 A294823 A294824 * A101265 A101879 A242622
Adjacent sequences: A294822 A294823 A294824 * A294826 A294827 A294828
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KEYWORD
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nonn,easy
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AUTHOR
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R. J. Mathar, Nov 09 2017
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STATUS
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approved
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