A208704 Number of nX3 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
4, 28, 196, 1372, 9604, 67228, 470596, 3294172, 23059204, 161414428, 1129900996, 7909306972, 55365148804, 387556041628, 2712892291396, 18990246039772, 132931722278404, 930522055948828, 6513654391641796, 45595580741492572
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..0..0....0..1..1....0..0..1....0..1..1....0..1..1....0..1..1....0..0..1 ..1..0..1....1..0..1....0..0..1....0..1..1....1..0..0....1..0..1....0..1..1 ..1..0..1....0..1..0....0..0..1....0..1..1....1..1..1....1..1..1....0..0..0 ..1..0..1....0..1..0....1..1..1....0..1..1....1..0..1....1..0..1....0..1..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A270471.
Formula
Empirical: a(n) = 7*a(n-1).
Empirical: a(n) = (A198480(n)+1)*2 = (A024075(n)+1)*4. [Martin Ettl, Nov 09 2012; revised Nov 13 2012]
Comments