OFFSET
0,3
LINKS
Robert Israel, Table of n, a(n) for n = 0..1646
D. Callan and T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 [math.CO] (2017), Table 1 No 227.
FORMULA
D-finite with recurrence (-n+1)*a(n) +3*(4*n-7)*a(n-1) +(-56*n+143)*a(n-2) +6*(23*n-80)*a(n-3) +(-214*n+979)*a(n-4) +9*(24*n-139)*a(n-5) +4*(-35*n+248)*a(n-6) +(49*n-418)*a(n-7) +3*(-n+13)*a(n-8) +2*(-2*n+17)*a(n-9)=0. - R. J. Mathar, Mar 11 2021
MAPLE
C := (1-sqrt(1-4*x))/2/x ;
(1 -6*x +12*x^2 -12*x^3 +6*x^4 -x^5 -x^2*(1 -x +x^2)^2*C)/(1 -7*x +16*x^2 -19*x^3 +11*x^4 -2*x^5 -x^6) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Nov 09 2017
STATUS
approved