OFFSET
1,2
LINKS
Robert Israel, Table of n, a(n) for n = 1..1810
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 189.
Lara Pudwell, Systematic Studies in Pattern Avoidance, 2005.
Index entries for linear recurrences with constant coefficients, signature (6,-12,13,-5,1).
FORMULA
G.f.: A(x) = -{(x-1)^4x}/{x^5-5x^4+13x^3-12x^2+6x-1}
MAPLE
f:= gfun:-rectoproc({a(n)-5*a(n+1)+13*a(n+2)-12*a(n+3)+6*a(n+4)-a(n+5), a(0) = 0, a(1) = 1, a(2) = 2, a(3) = 6, a(4) = 21, a(5) = 76}, a(n), remember):
map(f, [$1..30]); # Robert Israel, Jun 02 2016
MATHEMATICA
LinearRecurrence[{6, -12, 13, -5, 1}, {1, 2, 6, 21, 76}, 25] (* Jean-François Alcover, Sep 19 2018 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved