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A220971 Equals one maps: number of n X 2 binary arrays indicating the locations of corresponding elements equal to exactly one of their king-move neighbors in a random 0..1 n X 2 array. 1
2, 2, 9, 23, 58, 149, 379, 969, 2472, 6304, 16057, 40876, 104003, 264525, 672599, 1709802, 4345654, 11043371, 28060714, 71294653, 181127587, 460138081, 1168887760, 2969221064, 7542242881, 19157959588, 48662085275, 123602270581 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A220977.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 4*a(n-2) + 3*a(n-3) - 5*a(n-4) - 3*a(n-5) + 6*a(n-6) - 8*a(n-7) for n>10.

Empirical g.f.: x*(2 - 6*x + 9*x^2 - 11*x^3 + 6*x^4 - 2*x^5 - 15*x^6 + 21*x^7 - 14*x^8 + 8*x^9) / ((1 + x)*(1 - 2*x)*(1 - 3*x + 3*x^2 - 6*x^3 + 5*x^4 - 4*x^5)). - Colin Barker, Aug 03 2018

EXAMPLE

All solutions for n=3:

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

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

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

CROSSREFS

Cf. A220977.

Sequence in context: A192302 A128535 A180753 * A308519 A205390 A204265

Adjacent sequences:  A220968 A220969 A220970 * A220972 A220973 A220974

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 27 2012

STATUS

approved

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Last modified September 25 12:38 EDT 2021. Contains 347654 sequences. (Running on oeis4.)