A217958 Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..2 n X 2 array.

3, 17, 77, 343, 1523, 6761, 30013, 133231, 591427, 2625409, 11654477, 51735495, 229659507, 1019483609, 4525598973, 20089627615, 89180048899, 395879967217, 1757354367693, 7801087777591, 34629879796851, 153725814775369

Offset

1,1

Comments

Column 2 of A217964.

Links

R. H. Hardin, Table of n, a(n) for n = 1..179

Formula

Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - a(n-4).

Empirical g.f.: x*(1 + x)*(3 + 2*x + x^2) / (1 - 4*x - 2*x^2 + x^4). - Colin Barker, Jul 23 2018

Example

Some solutions for n=3:
..0..0....0..0....2..2....1..0....2..1....1..1....2..2....2..1....2..2....0..0
..0..0....1..2....2..2....0..0....1..0....2..2....2..2....1..1....1..0....0..2
..0..2....1..1....0..0....0..2....0..0....1..1....2..2....0..0....0..0....2..2

Crossrefs

Cf. A217964.

Sequence in context: A100233 A015525 A062224 * A093568 A164305 A202247

Adjacent sequences: A217955 A217956 A217957 * A217959 A217960 A217961

Keyword

nonn

Author

R. H. Hardin, Oct 16 2012

Status

approved