A294820 - OEIS

A294820

Number of permutations of [n] avoiding {1324, 2341, 1243}.

1, 1, 2, 6, 21, 76, 275, 989, 3544, 12696, 45578, 164194, 593966, 2158090, 7875503, 28862235, 106203597, 392291117, 1454239837, 5409048372, 20182045236, 75522431214, 283377791271, 1065990318403, 4019415215923, 15188857311110, 57514327098488, 218201177979480, 829305547436095

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OFFSET

0,3

LINKS

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 195.

MAPLE

C := (1-sqrt(1-4*x))/2/x ;

((1 -7*x +19*x^2 -25*x^3 +13*x^4 +4*x^5 -5*x^6 +x^7)*C -1 +7*x -19*x^2 +23*x^3 -7*x^4 -7*x^5 +4*x^6)/(x*(1 -x)^2*(1 -3*x +x^2)*(1 -x -x^2));

taylor(%, x=0, 40) ;

gfun[seriestolist](%) ;

CROSSREFS