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Permutations Number of permutations of [n] avoiding {2143, 1423, 1234}.
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1, 1, 2, 6, 21, 74, 259, 905, 3163, 11058, 38664, 135193, 472724, 1652965, 5779907, 20210571, 70670238, 247112450, 864077593, 3021418466, 10564988371, 36942575637, 129177037563, 451693114846, 1579434503132, 5522805791005, 19311585094940, 67526784937389, 236120787686511, 825643134498227, 2887024866494482, 10095054668915438, 35299359541791325, 123431207153135562, 431601680513369811, 1509180821596187857, 5277149870141113979
allocated for R. J. Mathar
Permutations of [n] avoiding {2143, 1423, 1234}.
1, 1, 2, 6, 21, 74, 259, 905, 3163, 11058, 38664, 135193, 472724, 1652965, 5779907, 20210571, 70670238, 247112450, 864077593, 3021418466, 10564988371, 36942575637, 129177037563, 451693114846, 1579434503132, 5522805791005, 19311585094940, 67526784937389, 236120787686511, 825643134498227, 2887024866494482, 10095054668915438, 35299359541791325, 123431207153135562, 431601680513369811, 1509180821596187857, 5277149870141113979
0,3
D. Callan, T. Mansour, <a href="http://arxiv.org/abs/1705.00933">Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns</a>, arXiv:1705.00933 [math.CO] (2017), Table 2 No 141.
(2*x^4-4*x^3+7*x^2-5*x+1)/(4*x^4-9*x^3+11*x^2-6*x+1) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;
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nonn,easy
R. J. Mathar, Nov 08 2017
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allocated for R. J. Mathar
allocated
approved