A246734 Number of length n+4 0..5 arrays with no pair in any consecutive five terms totalling exactly 5.

1566, 5430, 18966, 66294, 231414, 807630, 2818830, 9838974, 34342350, 119869158, 418392870, 1460364774, 5097280614, 17791629822, 62100187038, 216755476782, 756566753022, 2640732594966, 9217254934326, 32172052811478, 112293843388758

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + a(n-2) + a(n-3) + 5*a(n-4) + a(n-5) - a(n-6) - a(n-7).

Empirical g.f.: 6*x*(261 + 122*x + 185*x^2 + 400*x^3 + 51*x^4 - 98*x^5 - 77*x^6) / ((1 + x)*(1 - 4*x + 3*x^2 - 4*x^3 - x^4 + x^6)). - Colin Barker, Nov 06 2018

Example

Some solutions for n=4:
..5....2....5....3....5....5....3....3....5....2....5....2....3....3....3....5
..2....0....4....3....3....4....1....3....3....5....3....4....3....3....3....2
..1....4....4....0....4....4....1....1....1....4....3....0....4....1....4....4
..5....2....3....4....4....2....0....0....3....2....4....0....4....1....4....2
..1....0....5....3....5....4....1....0....3....4....3....4....4....5....4....2
..5....2....5....0....4....0....1....0....5....4....4....0....4....5....4....2
..1....0....5....0....3....2....1....3....5....4....3....2....0....5....4....2
..2....0....3....4....5....0....2....1....1....5....5....2....0....3....0....1

Crossrefs

Column 5 of A246737.

Sequence in context: A072394 A243528 A237673 * A237467 A035890 A252109

Adjacent sequences: A246731 A246732 A246733 * A246735 A246736 A246737

Keyword

nonn

Author

R. H. Hardin, Sep 02 2014

Status

approved