A294805 Number of permutations of [n] avoiding {1324, 2341, 2413}.

1, 1, 2, 6, 21, 74, 255, 857, 2815, 9063, 28677, 89389, 275034, 836689, 2520128, 7524372, 22291317, 65581700, 191743857, 557466281, 1612517029, 4642784877, 13311163941, 38016320047, 108187223460, 306869427745, 867780176654, 2447031902418, 6882225083349, 19308762485774, 54048777806931

Offset

0,3

Links

Table of n, a(n) for n=0..30.

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 132.

Index entries for linear recurrences with constant coefficients, signature (9,-30,45,-30,9,-1).

Maple

(1 -8*x +23*x^2 -27*x^3 +12*x^4 -4*x^5 +x^6)/(1 -3*x +x^2)^3 ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;

Crossrefs

Sequence in context: A116777 A294768 A116793 * A116805 A116790 A116817

Adjacent sequences: A294802 A294803 A294804 * A294806 A294807 A294808

Keyword

nonn,easy

Author

R. J. Mathar, Nov 09 2017

Status

approved