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A232032
Number of (n+1) X (2+1) 0..1 arrays with every element equal to some horizontal, vertical or antidiagonal neighbor, with top left element zero.
1
11, 76, 521, 3588, 24719, 170270, 1172854, 8078859, 55648831, 383320506, 2640389883, 18187544432, 125279518221, 862950891715, 5944181874953, 40944737993493, 282035712335780, 1942719551542674, 13381848790314938
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) - 5*a(n-3) - 2*a(n-4) - a(n-5) + 2*a(n-6) + 2*a(n-7) for n>8.
Empirical g.f.: x*(11 - x - 11*x^2 - 4*x^3 + 5*x^4 + 5*x^5 - x^7) / (1 - 7*x + 5*x^3 + 2*x^4 + x^5 - 2*x^6 - 2*x^7). - Colin Barker, Oct 02 2018
EXAMPLE
Some solutions for n=6:
..0..0..0....0..0..0....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1
..1..0..0....1..1..0....0..0..1....0..0..0....0..1..1....0..1..1....0..1..0
..1..1..0....1..1..0....1..1..0....0..1..0....1..0..0....0..0..1....0..0..0
..1..1..1....1..0..1....0..0..1....1..1..1....1..1..0....0..0..0....1..0..1
..1..0..1....1..0..1....0..0..1....0..1..0....1..1..1....0..1..0....1..1..0
..1..0..1....0..0..0....1..1..1....0..0..0....0..0..1....1..1..0....0..0..0
..1..0..1....1..1..1....0..0..1....1..1..1....1..1..1....1..1..0....1..1..0
CROSSREFS
Column 2 of A232038.
Sequence in context: A256597 A245561 A056914 * A272395 A305727 A218395
KEYWORD
nonn
AUTHOR
R. H. Hardin, Nov 17 2013
STATUS
approved