OFFSET
1,1
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,0,-6,4).
FORMULA
From Andrew Howroyd, Mar 09 2024: (Start)
a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).
G.f.: x*(9 - 6*x - 22*x^2 + 12*x^3)/((1 - x)*(1 - 2*x)*(1 - 2*x^2)). (End)
EXAMPLE
Some solutions for 5X5
..1..0..1..0..1....1..2..1..0..1....1..0..1..0..1....0..1..0..1..0
..1..0..1..0..1....0..0..0..2..0....2..0..2..0..2....1..1..1..1..1
..0..1..0..1..0....1..2..1..0..1....0..1..0..1..0....1..0..1..0..1
..0..1..0..1..0....0..0..0..2..0....0..2..0..2..0....1..1..1..1..1
..0..1..0..1..0....1..2..1..0..1....1..0..1..0..1....0..1..0..1..0
PROG
(PARI) Vec((9 - 6*x - 22*x^2 + 12*x^3)/((1 - x)*(1 - 2*x)*(1 - 2*x^2)) + O(x^32)) \\ Andrew Howroyd, Mar 09 2024
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. H. Hardin, Jan 08 2011
EXTENSIONS
a(15) onwards from Andrew Howroyd, Mar 09 2024
STATUS
approved