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

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) ;
gfun[seriestolist](%) ;

Mathematica

LinearRecurrence[{9, -33, 66, -78, 55, -23, 4}, {1, 1, 2, 6, 21, 74, 253, 843}, 30] (* Harvey P. Dale, Jun 06 2022 *)

Crossrefs

Sequence in context: A116827 A116780 A116777 * A116793 A294805 A116805

Adjacent sequences: A294765 A294766 A294767 * A294769 A294770 A294771

Keyword

nonn,easy

Author

R. J. Mathar, Nov 08 2017

Status

approved