A232584 Number of (n+1)X(3+1) 0..2 arrays with every element next to itself plus and minus one within the range 0..2 horizontally or antidiagonally, with no adjacent elements equal.
2, 12, 42, 122, 332, 882, 2322, 6092, 15962, 41802, 109452, 286562, 750242, 1964172, 5142282, 13462682, 35245772, 92274642, 241578162, 632459852, 1655801402, 4334944362, 11349031692, 29712150722, 77787420482, 203650110732
Offset: 1
Keywords
Examples
Some solutions for n=7 ..0..1..2..1....2..1..0..1....0..1..0..1....2..1..0..1....2..1..2..1 ..2..1..0..1....0..1..2..1....2..1..2..1....2..1..2..0....0..1..0..1 ..2..1..2..1....2..1..0..1....2..1..0..2....2..0..1..0....0..1..2..1 ..0..1..0..1....2..1..2..0....0..2..1..2....1..2..1..0....0..1..0..2 ..0..1..2..1....2..0..1..0....1..0..1..0....1..0..2..1....0..2..1..2 ..0..1..0..2....1..2..1..2....1..2..1..2....2..1..0..2....1..0..1..2 ..0..2..1..2....1..0..1..2....1..0..1..0....0..2..1..0....1..2..1..0 ..1..0..1..2....1..2..1..0....1..2..1..2....1..0..1..2....1..0..1..2
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 4*a(n-1) -4*a(n-2) +a(n-3) = 2*A122678(n).
Empirical: G.f.: -2*x*(1+x)^2 / ( (x-1)*(x^2-3*x+1) ). - R. J. Mathar, Nov 23 2014
Comments