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A196204
Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 2,0,3,4,1 for x=0,1,2,3,4.
2
3, 5, 8, 11, 18, 28, 43, 67, 105, 164, 257, 404, 636, 1003, 1585, 2509, 3978, 6317, 10046, 15998, 25509, 40723, 65083, 104122, 166737, 267242, 428678, 688151, 1105443, 1776907, 2857894, 4598959, 7404324, 11926298, 19217795, 30978737, 49954191
OFFSET
1,1
COMMENTS
Every 0 is next to 0 2's, every 1 is next to 1 0's, every 2 is next to 2 3's, every 3 is next to 3 4's, every 4 is next to 4 1's.
Column 2 of A196210.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) - a(n-4) - a(n-5).
Empirical g.f.: x*(1 + x + x^2)*(3 - 4*x - x^2) / ((1 - x - x^2)*(1 - x - x^3)). - Colin Barker, Mar 01 2018
EXAMPLE
Some solutions for n=4:
..0..0....0..1....1..0....1..0....0..1....0..0....1..1....1..0....0..1....0..0
..0..0....0..1....1..0....1..1....0..1....1..1....0..0....1..0....1..1....0..0
..0..0....1..1....1..1....0..1....0..1....1..1....0..0....1..0....1..0....0..0
..1..1....1..0....0..1....0..1....0..1....0..0....0..0....1..0....1..0....0..0
CROSSREFS
Cf. A196210.
Sequence in context: A320594 A227563 A180619 * A220483 A136684 A215751
KEYWORD
nonn
AUTHOR
R. H. Hardin, Sep 29 2011
STATUS
approved