A246744 Number of length 7+4 0..n arrays with no pair in any consecutive five terms totalling exactly n.

2, 68, 10812, 135776, 2818830, 19906740, 162700376, 766650656, 3696053370, 13019727620, 45166073172, 128894476608, 358710268742, 876273071156, 2086036196400, 4529314688960, 9603337631346, 19024638124356, 36902088232940

Offset: 1

Author

R. H. Hardin, Sep 02 2014

Keywords

• nonn

Comments

Row 7 of A246737

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..56

Formula

Empirical: a(n) = 3*a(n-1) +6*a(n-2) -26*a(n-3) -9*a(n-4) +99*a(n-5) -24*a(n-6) -216*a(n-7) +126*a(n-8) +294*a(n-9) -252*a(n-10) -252*a(n-11) +294*a(n-12) +126*a(n-13) -216*a(n-14) -24*a(n-15) +99*a(n-16) -9*a(n-17) -26*a(n-18) +6*a(n-19) +3*a(n-20) -a(n-21)