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A294768

Number of permutations of [n] avoiding {2341, 3142, 4123}.

1, 1, 2, 6, 21, 74, 253, 843, 2772, 9080, 29759, 97686, 321033, 1055596, 3471365, 11415280, 37535830, 123420905, 405812530, 1334326344, 4387329985, 14425801573, 47432972821, 155962779313, 512816020062, 1686173040104, 5544248055746, 18229852104876, 59940951879918

(list; graph; refs; listen; history; text; internal format)

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 2 No 128.

Index entries for linear recurrences with constant coefficients, signature (9,-33,66,-78,55,-23,4).

FORMULA

G.f.: (-1+8 x-26 x^2+45 x^3-45 x^4+26 x^5-8 x^6+x^7)/(-1+9 x-33 x^2+66 x^3-78 x^4+55 x^5-23 x^6+4 x^7) - Harvey P. Dale, Jun 06 2022

MAPLE

(x^2-3*x+1)*(x-1)^5/(4*x^7-23*x^6+55*x^5-78*x^4+66*x^3-33*x^2+9*x-1) ;

taylor(%, x=0, 40) ;