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A220542 Equals one maps: number of n X 2 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and vertical neighbors in a random 0..2 n X 2 array. 4
2, 8, 38, 176, 816, 3616, 15362, 63484, 258180, 1041120, 4180554, 16752240, 67064038, 268355784, 1073601356, 4294721316, 17179440926, 68718734848, 274876627338, 1099509429172, 4398042746324, 17592179617352, 70368733235570 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A220545.

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) - 7*a(n-2) - 6*a(n-3) + 7*a(n-4) + 4*a(n-5) for n>10.

Empirical g.f.: 2*x*(1 - 2*x + 2*x^2 + 8*x^3 + 30*x^4 + 58*x^5 + 68*x^6 + 68*x^7 + 45*x^8 + 12*x^9) / ((1 - 4*x)*(1 - x - x^2)^2). - Colin Barker, Feb 21 2018

EXAMPLE

Some solutions for n=3:

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

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

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

CROSSREFS

Cf. A220545.

Sequence in context: A220806 A192529 A155609 * A199213 A123164 A002003

Adjacent sequences:  A220539 A220540 A220541 * A220543 A220544 A220545

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 15 2012

STATUS

approved

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Last modified February 17 12:32 EST 2020. Contains 331996 sequences. (Running on oeis4.)