OFFSET
0,3
LINKS
E. Deutsch, Counting tilings with L-tiles and squares, Problem 10877, Amer. Math. Monthly, 110 (March 2003), 245-246.
Index entries for linear recurrences with constant coefficients, signature (1,5,4,0,-1).
FORMULA
G.f.: ( 1-x^2-x^3 ) / ( (1+x)*(x^4-x^3-3*x^2-2*x+1) ).
a(n) = a(n-1)+5a(n-2)+4a(n-3)-a(n-5) for n>=5; a(0)=1, a(1)=1, a(2)=5, a(3)=13, a(4)=42.
MAPLE
a[0]:=1:a[1]:=1:a[2]:=5:a[3]:=13:a[4]:=42: for n from 5 to 30 do a[n]:=a[n-1]+5*a[n-2]+4*a[n-3]-a[n-5] od: seq(a[n], n=0..30);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Apr 15 2005
STATUS
approved