A249284 Number of length n+3 0..2 arrays with no four consecutive terms having the sum of any three elements equal to three times the fourth.

66, 168, 428, 1094, 2792, 7132, 18232, 46616, 119176, 304696, 779066, 1992002, 5093330, 13023126, 33299000, 85142802, 217703012, 556648464, 1423304428, 3639273226, 9305324178, 23792953554, 60836640416, 155554327024, 397739724496

Offset: 1

Author

R. H. Hardin, Oct 24 2014

Keywords

• nonn

Comments

Column 2 of A249290

Examples

			Some solutions for n=9
..1....0....2....2....1....1....0....1....1....1....0....1....1....2....2....1
..1....0....1....0....0....1....1....0....1....0....0....1....1....0....1....0
..0....1....0....0....2....0....2....2....2....2....0....1....2....0....0....2
..1....0....0....0....2....1....0....2....2....0....2....2....1....0....0....2
..0....1....2....1....0....0....0....0....1....2....2....2....2....1....1....2
..2....0....2....0....0....0....0....1....2....1....0....0....2....0....1....0
..0....1....2....0....0....1....2....0....2....2....2....2....1....0....0....0
..2....1....0....1....1....1....0....1....2....1....0....2....0....1....0....2
..0....0....0....1....2....0....2....0....0....2....2....1....0....0....2....2
..2....0....2....1....2....1....1....0....0....1....1....2....0....2....1....2
..2....0....2....2....1....0....2....0....1....2....2....0....2....0....2....1
..2....2....1....2....2....0....2....1....2....0....1....0....2....0....2....0
		

Links

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

Formula

Empirical: a(n) = a(n-1) +2*a(n-2) +3*a(n-3) +7*a(n-4) +a(n-5) -6*a(n-6) -12*a(n-7) -14*a(n-8) -14*a(n-9) -7*a(n-10) +3*a(n-11) +2*a(n-12)