A217639 Number of nX2 arrays of the minimum value of corresponding elements and their horizontal, vertical or antidiagonal neighbors in a random 0..2 nX2 array.
3, 9, 27, 91, 293, 959, 3121, 10171, 33141, 107985, 351855, 1146471, 3735623, 12172023, 39660897, 129229689, 421077529, 1372024391, 4470556607, 14566706329, 47463649813, 154653907527, 503918919165, 1641951898617, 5350079020329
Offset: 1
Keywords
Examples
Some solutions for n=3 ..2..1....1..1....0..0....2..0....2..1....1..1....0..0....0..0....1..0....2..2 ..1..0....1..1....0..1....0..0....0..0....1..0....0..1....0..0....0..0....2..1 ..0..0....2..2....2..2....0..0....0..0....0..0....1..1....0..2....0..0....1..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = 2*a(n-1) +3*a(n-2) +3*a(n-3) +2*a(n-4) -a(n-6).
Empirical: G.f.: x*(3+3*x+x^3-3*x^4+x^5) / ( 1-2*x-3*x^2-3*x^3-2*x^4+x^6 ). - R. J. Mathar, Jul 10 2015
Comments