A294798 Number of permutations of [n] avoiding {1243, 1324, 4231}.

1, 1, 2, 6, 21, 73, 238, 721, 2044, 5492, 14178, 35610, 87938, 215295, 525787, 1286294, 3160692, 7812235, 19435271, 48669058, 122640467, 310825886, 791852703, 2026485203, 5206520173, 13421671869, 34697109772, 89909564367, 233436502611, 607059621989, 1580760867164, 4120657531699

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 75.

Index entries for linear recurrences with constant coefficients, signature (15,-101,404,-1070,1978,-2618,2500,-1709,815,-257,48,-4).

Maple

x/(1-3*x+x^2) -(2-4*x-4*x^2-x^3) /(1-2*x)^2 +(3 -20*x +55*x^2 -83*x^3 +74*x^4 -38*x^5 +12*x^6 -2*x^7) /(1-x)^8 ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;

Crossrefs

Sequence in context: A294762 A294797 A294763 * A294799 A294693 A116757

Adjacent sequences: A294795 A294796 A294797 * A294799 A294800 A294801

Keyword

nonn,easy

Author

R. J. Mathar, Nov 09 2017

Status

approved