A220574 Equals one maps: number of n X 3 binary arrays indicating the locations of corresponding elements equal to exactly one of their horizontal and antidiagonal neighbors in a random 0..1 n X 3 array.

4, 21, 91, 375, 1487, 5835, 22775, 88683, 344975, 1341395, 5214791, 20271307, 78797247, 306290211, 1190562423, 4627750267, 17988173039, 69920406547, 271782019879, 1056422029931, 4106332901663, 15961395217283, 62042250575063

Offset

1,1

Comments

Column 3 of A220579.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + 4*a(n-2) + 2*a(n-3) - 12*a(n-4) - 16*a(n-5) for n>6.

Empirical g.f.: x*(4 + 9*x + 12*x^2 + 10*x^3 + 4*x^4 + 8*x^5) / (1 - 3*x - 4*x^2 - 2*x^3 + 12*x^4 + 16*x^5). - Colin Barker, Aug 01 2018

Example

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

Crossrefs

Cf. A220579.

Sequence in context: A174797 A328345 A371309 * A231377 A017967 A292308

Adjacent sequences: A220571 A220572 A220573 * A220575 A220576 A220577

Keyword

nonn

Author

R. H. Hardin, Dec 16 2012

Status

approved