OFFSET
0,3
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
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 71.
Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
FORMULA
G.f.: (1 - 7*x + 22*x^2 - 38*x^3 + 43*x^4 - 25*x^5 + 17*x^6 + 2*x^7 - 4*x^8) / (1 - x)^8.
From Colin Barker, Nov 11 2017: (Start)
a(n) = (25200 - 52056*n + 48650*n^2 - 20881*n^3 + 4340*n^4 - 154*n^5 - 70*n^6 + 11*n^7) / 5040 for n>0.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.
(End)
MAPLE
-(4*x^8-2*x^7-17*x^6+25*x^5-43*x^4+38*x^3-22*x^2+7*x-1)/((x-1)^8) ;
taylor(%, x=0, 40) ;
gfun[seriestolist](%) ;
PROG
(PARI) Vec((1 - 7*x + 22*x^2 - 38*x^3 + 43*x^4 - 25*x^5 + 17*x^6 + 2*x^7 - 4*x^8) / (1 - x)^8 + O(x^40)) \\ Colin Barker, Nov 11 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Nov 08 2017
STATUS
approved