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A220806 Equals one maps: number of n X 2 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal, vertical and antidiagonal neighbors in a random 0..2 n X 2 array. 2
2, 8, 38, 168, 726, 3088, 12974, 54000, 223118, 916552, 3747670, 15266264, 61997350, 251143328, 1015242974, 4097067104, 16510377630, 66454603032, 267215894086, 1073591223944, 4310358413046, 17295539333552, 69365195543182 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A220810.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 7*a(n-1) - 11*a(n-2) - 3*a(n-3) - 4*a(n-4).

Empirical g.f.: 2*x*(1 - 3*x + 2*x^2 - 2*x^3) / ((1 - 4*x)*(1 - 3*x - x^2 - x^3)). - Colin Barker, Mar 13 2018

EXAMPLE

Some solutions for n=3:

..0..0....0..0....1..1....0..0....1..0....0..1....0..0....0..1....0..0....1..0

..0..0....0..1....1..0....1..0....1..0....1..0....0..0....0..0....0..0....0..0

..1..0....1..0....0..1....1..0....0..0....1..1....0..0....1..0....1..1....1..0

CROSSREFS

Cf. A220810.

Sequence in context: A053520 A202744 A112738 * A192529 A155609 A220542

Adjacent sequences:  A220803 A220804 A220805 * A220807 A220808 A220809

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 22 2012

STATUS

approved

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Last modified August 17 19:38 EDT 2022. Contains 356189 sequences. (Running on oeis4.)