A265451 Number of n X 1 0..n+1-2 arrays with each element differing from its horizontal and vertical neighbors by one or two.
1, 1, 2, 12, 66, 360, 1864, 9358, 45642, 217590, 1017626, 4684896, 21284488, 95624666, 425523864, 1878025074, 8229470812, 35836393568, 155196577484, 668832795812, 2869861291134, 12266161148622, 52243167132940, 221803857150698, 938974990229088, 3964558585350392
Offset: 0
Keywords
Examples
Some solutions for n=4 ..3....3....1....2....2....0....3....0....0....1....2....2....1....0....0....3 ..2....1....2....0....1....1....1....1....2....3....3....0....0....1....1....2 ..3....2....1....2....0....3....0....0....1....2....2....1....1....3....2....0 ..2....1....3....1....1....2....1....1....0....1....0....2....2....1....0....2
Links
- Alois P. Heinz, Table of n, a(n) for n = 0..500 (terms n = 1..210 from R. H. Hardin)
Extensions
a(0)=1 prepended by Alois P. Heinz, Oct 25 2022