OFFSET
0,3
COMMENTS
The old entry with this sequence number was a duplicate of A007737.
REFERENCES
Jaime Rangel-Mondragon, Polyominoes and Related Families, The Mathematica Journal, 9:3 (2005), 609-640.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2430
Index entries for linear recurrences with constant coefficients, signature (2,0,3,2,1,-1).
FORMULA
G.f.: -(x^3+x-1)/(x^6-x^5-2*x^4-3*x^3-2*x+1). - Alois P. Heinz, Sep 24 2009
MAPLE
a:= n-> (Matrix([[1, 1, 0, 0, 1, 1]]). Matrix (6, (i, j)-> if i=j-1 then 1 elif j=1 then [2, 0, 3, 2, 1, -1][i] else 0 fi)^n)[1, 2]: seq(a(n), n=0..30); # Alois P. Heinz, Sep 24 2009
MATHEMATICA
LinearRecurrence[{2, 0, 3, 2, 1, -1}, {1, 1, 2, 6, 17, 43}, 40] // Rest (* Jean-François Alcover, Feb 18 2016 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Oct 04 2008
EXTENSIONS
More terms from Alois P. Heinz, Sep 24 2009
a(0)=1 prepended by Alois P. Heinz, Jul 25 2023
STATUS
approved