A266019 Number of nX2 integer arrays with each element equal to the number of horizontal, vertical and antidiagonal neighbors exactly one smaller than itself.

3, 7, 14, 42, 99, 259, 719, 1784, 4792, 12479, 32263, 86025, 222663, 585072, 1535472, 4002444, 10527738, 27516774, 72060109, 188952481, 494214824, 1295507675, 3392305134, 8882420053, 23272852966, 60933892273, 159611564865, 418043981246

Offset

1,1

Comments

Column 2 of A266025.

Links

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

Formula

Empirical: a(n) = a(n-1) +2*a(n-2) +6*a(n-3) -a(n-4) +20*a(n-5) -25*a(n-6) -37*a(n-7) -53*a(n-8) -52*a(n-9) +47*a(n-10) +74*a(n-11) +77*a(n-12) +30*a(n-13) -29*a(n-14) -34*a(n-15) -34*a(n-16) -a(n-17) -6*a(n-18) +11*a(n-19) +a(n-20) +a(n-21)

Example

Some solutions for n=4
..1..1....0..1....1..0....0..1....1..0....1..0....0..1....1..0....1..0....1..0
..0..1....1..2....1..1....2..1....1..2....1..1....2..1....1..2....1..2....2..1
..1..1....2..0....1..2....0..2....2..1....2..2....2..0....1..0....1..2....2..1
..2..0....1..1....0..0....0..1....0..1....0..1....1..1....1..1....0..1....0..1

Crossrefs

Cf. A266025.

Sequence in context: A146936 A184264 A298913 * A146155 A106363 A128658

Adjacent sequences: A266016 A266017 A266018 * A266020 A266021 A266022

Keyword

nonn

Author

R. H. Hardin, Dec 20 2015

Status

approved