A218843 Unmatched value maps: number of 2 X n binary arrays indicating the locations of corresponding elements not equal to any horizontal or antidiagonal neighbor in a random 0..1 2 X n array.

1, 7, 20, 57, 156, 438, 1220, 3398, 9468, 26380, 73496, 204780, 570556, 1589672, 4429140, 12340436, 34382820, 95797176, 266909376, 743660900, 2071982512, 5772942284, 16084528900, 44814595084, 124862092120, 347889834096

Offset: 1

Author

R. H. Hardin, Nov 07 2012

Keywords

• nonn

Comments

Row 2 of A218842.

Examples

			Some solutions for n=3:
..0..0..0....0..0..1....1..0..0....1..0..0....1..1..0....0..0..0....0..0..0
..0..1..1....0..0..1....1..0..1....0..1..1....0..0..0....0..0..1....1..0..0
		

Links

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

Crossrefs

Cf. A218842.

Formula

Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) + 2*a(n-5) + 2*a(n-6) - 2*a(n-7) for n>9.

Empirical g.f.: x*(1 + 5*x + 5*x^2 + 7*x^3 + x^4 + 7*x^5 + x^6 - 2*x^8) / (1 - 2*x - x^2 - 3*x^3 - 2*x^5 - 2*x^6 + 2*x^7). - Colin Barker, Jul 24 2018