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A277653
Number of n X 2 0..2 arrays with every element equal to some element at offset (-1,0) (-1,1) (0,-1) (0,1) or (1,0) both plus 1 mod 3 and minus 1 mod 3, with new values introduced in order 0..2.
1
0, 0, 1, 2, 8, 28, 98, 346, 1218, 4290, 15110, 53218, 187438, 660170, 2325166, 8189402, 28843662, 101589450, 357805342, 1260216122, 4438571726, 15632968522, 55060438334, 193926819802, 683024192622, 2405660280426, 8472908349854
OFFSET
1,4
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - 2*a(n-4).
Empirical g.f.: x^3*(1 - x) / (1 - 3*x - 2*x^2 + 2*x^4). - Colin Barker, Feb 05 2019
EXAMPLE
All solutions for n=4:
..0..1. .0..1
..2..2. .2..2
..1..0. .1..0
..1..2. .2..1
CROSSREFS
Column 2 of A277659.
Sequence in context: A106731 A318010 A291383 * A066796 A104934 A056711
KEYWORD
nonn
AUTHOR
R. H. Hardin, Oct 26 2016
STATUS
approved