OFFSET
1,2
COMMENTS
Row 2 of A229586.
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
Index entries for linear recurrences with constant coefficients, signature (6,-9).
FORMULA
a(n) = 6*a(n-1) - 9*a(n-2) for n>4.
From Oboifeng Dira, Mar 04 2015: (Start)
a(n) = 4*(3^(n-2) + 4*(2*n-3)*3^(n-4)) for n>2.
G.f.: (x + x^3 + 2*x^4)/(1-3*x)^2 (except for first term).
(End)
EXAMPLE
Some solutions for n=3
..0..1..0....0..1..0....0..1..2....0..1..1....0..1..0....0..1..1....0..1..2
..2..1..1....2..2..1....2..1..1....0..2..0....0..1..1....0..2..1....1..0..2
MATHEMATICA
LinearRecurrence[{6, -9}, {0, 6, 28, 116}, 30] (* Harvey P. Dale, Mar 06 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 26 2013
STATUS
approved