A246002 Number of length 7+2 0..n arrays with no pair in any consecutive three terms totalling exactly n.

2, 82, 5572, 75260, 728358, 4108062, 18838280, 66983128, 209732170, 567864650, 1413132492, 3203059092, 6839534702, 13687432150, 26203871248, 47834595632, 84386904210, 143553121218, 237664797140, 382348873900, 601693049782

Offset: 1

Author

R. H. Hardin, Aug 09 2014

Keywords

• nonn

Comments

Row 7 of A245995

Examples

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

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +4*a(n-2) -20*a(n-3) +56*a(n-5) -28*a(n-6) -84*a(n-7) +70*a(n-8) +70*a(n-9) -84*a(n-10) -28*a(n-11) +56*a(n-12) -20*a(n-14) +4*a(n-15) +3*a(n-16) -a(n-17)