A294824 Number of permutations of [n] avoiding {1324, 2413, 2431}.

1, 1, 2, 6, 21, 77, 285, 1053, 3875, 14212, 52021, 190301, 696532, 2553047, 9377034, 34525630, 127466481, 471935813, 1752332838, 6525032251, 24363932865, 91214649344, 342358204917, 1288067835421, 4857138874476, 18354766803127, 69500599635905, 263661684179088, 1002016365217651

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 212.

Maple

C := (1-sqrt(1-4*x))/2/x ;
1 +x*(1 -4*x +4*x^2 -x^3 -x*(1 -4*x +2*x^2)*C)/((1 -3*x +x^2)*(1 -3*x +x^2 -x*(1 -2*x)*C)) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;

Crossrefs

Sequence in context: A151287 A294822 A294823 * A294825 A101265 A101879

Adjacent sequences: A294821 A294822 A294823 * A294825 A294826 A294827

Keyword

nonn,easy

Author

R. J. Mathar, Nov 09 2017

Status

approved