A221899 Number of 2 X n arrays of occupancy after each element stays put or moves to some horizontal, vertical or antidiagonal neighbor, without move-in move-out straight through or left turns.
3, 31, 258, 2241, 19408, 167960, 1453952, 12585637, 108943526, 943035150, 8163084148, 70661144632, 611655753520, 5294603734144, 45831055372945, 396721972412987, 3434097733826959, 29726176177614458, 257315201439500033
Offset: 1
Keywords
Examples
Some solutions for n=3: ..0..2..3....0..0..0....0..3..0....2..0..2....1..1..2....0..4..1....1..2..1 ..1..0..0....3..2..1....2..0..1....2..0..0....0..2..0....0..1..0....0..1..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Crossrefs
Cf. A221898.
Formula
Empirical: a(n) = 5*a(n-1) + 26*a(n-2) + 45*a(n-3) + 34*a(n-4) - 2*a(n-5) - 4*a(n-6) + a(n-7).
Empirical g.f.: x*(3 + 16*x + 25*x^2 + 10*x^3 - 2*x^4 - 4*x^5 + x^6) / (1 - 5*x - 26*x^2 - 45*x^3 - 34*x^4 + 2*x^5 + 4*x^6 - x^7). - Colin Barker, Aug 11 2018
Comments