A301842 Number of 2Xn 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero.
2, 8, 25, 81, 263, 855, 2778, 9027, 29333, 95316, 309725, 1006437, 3270370, 10626915, 34531665, 112209036, 364618033, 1184809305, 3849982618, 12510339087, 40651763813, 132096011916, 429239834325, 1394794836717, 4532320816850
Offset: 1
Keywords
Examples
Some solutions for n=5 ..0..1..1..0..0. .0..0..1..0..0. .0..0..0..1..1. .0..1..0..1..1 ..0..0..1..0..0. .0..0..0..1..1. .1..0..1..0..0. .1..1..0..0..0
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A301841.
Formula
Empirical: a(n) = 3*a(n-1) +a(n-2) -2*a(n-4) for n>6
Comments