A248429 Number of length n+2 0..4 arrays with every three consecutive terms having the sum of some two elements equal to twice the third.

29, 45, 69, 101, 165, 261, 389, 645, 1029, 1541, 2565, 4101, 6149, 10245, 16389, 24581, 40965, 65541, 98309, 163845, 262149, 393221, 655365, 1048581, 1572869, 2621445, 4194309, 6291461, 10485765, 16777221, 25165829, 41943045, 67108869, 100663301

Offset: 1

Author

R. H. Hardin, Oct 06 2014

Keywords

• nonn

Examples

			Some solutions for n=6:
..1....2....2....2....0....4....1....2....1....2....4....0....2....4....0....2
..3....4....3....1....4....0....0....4....3....4....3....2....0....2....1....4
..2....3....1....3....2....2....2....3....2....0....2....4....4....0....2....0
..1....2....2....2....0....1....4....2....1....2....1....3....2....4....0....2
..0....4....0....1....4....3....3....1....3....4....0....2....3....2....4....1
..2....0....4....0....2....2....2....0....2....3....2....1....4....0....2....3
..4....2....2....2....0....1....4....2....1....2....1....3....2....4....0....2
..3....4....0....1....4....3....3....1....0....1....3....2....3....2....1....1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Column 4 of A248433.

Formula

Empirical: a(n) = a(n-1) + 4*a(n-3) - 4*a(n-4).

Empirical g.f.: x*(29 + 16*x + 24*x^2 - 84*x^3) / ((1 - x)*(1 - 4*x^3)). - Colin Barker, Nov 08 2018