OFFSET
1,2
LINKS
D. Callan, T. Mansour, Enumeration of small Wilf classes avoiding 1324 and two other 4-letter patterns, arXiv:1705.00933 (2017), Table 2 No 19.
Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).
FORMULA
G.f.: -((6x^8-7x^7-7x^6+4x^5+11x^4+x^3+6x^2-3x+1)*x)/(x-1)^5.
For n >= 5, a(n) = (n^4 - 5n^3 + 9n^2 - 57n + 202)/2. - Franklin T. Adams-Watters, Sep 16 2006
MATHEMATICA
(1 - 3x + 6x^2 + x^3 + 11x^4 + 4x^5 - 7x^6 - 7x^7 + 6x^8)/(1 - x)^5 + O[x]^30 // CoefficientList[#, x]& (* Jean-François Alcover, May 06 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved