A294807 Number of permutations of [n] avoiding {1324, 1342, 3421}.

1, 1, 2, 6, 21, 75, 259, 853, 2684, 8120, 23782, 67845, 189493, 520359, 1409742, 3778514, 10042552, 26517095, 69668495, 182357337, 476027280, 1240285036, 3227591882, 8393207561, 21819385961, 56722065995, 147485931154, 383621798278, 998279190044, 2599085844715, 6770473854147, 17646032160125

Offset

0,3

Links

Table of n, a(n) for n=0..31.

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 151.

Index entries for linear recurrences with constant coefficients, signature (13,-72,221,-409,464,-312,112,-16).

Formula

a(n) = 13*a(n-1)-72*a(n-2)+221*a(n-3)-409*a(n-4)+464*a(n-5)-312*a(n-6)+112*a(n-7)-16*a(n-8). - Wesley Ivan Hurt, Oct 18 2021

Maple

(1 -12*x +61*x^2 -169*x^3 +275*x^4 -263*x^5 +136*x^6 -29*x^7 +x^8)/((1 -3*x +x^2)*(1 -2*x)^4*(1 -x)^2) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;

Crossrefs

Sequence in context: A116841 A116814 A294806 * A294771 A294814 A116816

Adjacent sequences: A294804 A294805 A294806 * A294808 A294809 A294810

Keyword

nonn,easy

Author

R. J. Mathar, Nov 09 2017

Status

approved