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A196537
Number of nX1 0..4 arrays with each element equal to the number its horizontal and vertical neighbors less than or equal to itself
3
1, 3, 2, 7, 19, 35, 77, 176, 377, 819, 1801, 3927, 8562, 18711, 40855, 89179, 194729, 425184, 928305, 2026855, 4425441, 9662395, 21096706, 46062279, 100571611, 219586403, 479441557, 1046805072, 2285577449, 4990293595, 10895727817
OFFSET
1,2
COMMENTS
Column 1 of A196544
LINKS
FORMULA
Empirical: a(n) = a(n-1) +a(n-2) +3*a(n-3) +a(n-4).
Empirical: G.f. x*(x-1)*(x^2+3*x+1) / ( -1+x+x^2+3*x^3+x^4 ). - R. J. Mathar, Jul 25 2012
EXAMPLE
All solutions for n=4
..0....0....1....0....0....1....0
..2....1....0....2....2....1....2
..2....2....2....1....1....2....0
..0....0....0....1....0....0....1
CROSSREFS
Sequence in context: A104528 A177115 A316087 * A173099 A111928 A348695
KEYWORD
nonn
AUTHOR
R. H. Hardin Oct 03 2011
STATUS
approved