OFFSET
0,2
COMMENTS
Tiling algorithm see A351322.
LINKS
Index entries for linear recurrences with constant coefficients, signature (6,33,3,-40,15).
FORMULA
G.f.: (1-3*x-7*x^2+3*x^3-2*x^4) / (1-6*x-33*x^2-3*x^3+40*x^4-15*x^5).
a(n) = 6*a(n-1) + 33*a(n-2) + 3*a(n-3) - 40*a(n-4) + 15*a(n-5).
EXAMPLE
a(2)=44
The number of tilings (mirroring included) using r trominoes
___ ___ ___
r=1: | _| | |_| r=2: | _| r=0: 22 = A030186(3)
|_|3| |___| |_| |
|___| |_2_| |___|
4*3 + 4*2 + 2*1 + 22 = 44
Legend:
___ ___ ___
|_2_| stands for |___| or |_|_|
_ _ _ _
_|3| _| | _|_| _|_|
|___| stands for |_|_| or |___| or |_|_|
PROG
(Maxima) See A352589.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gerhard Kirchner, May 09 2022
STATUS
approved