A221964 - OEIS

%I #7 Aug 11 2018 14:07:51

%S 11,121,671,4961,34111,241153,1690623,11888129,83512319,586864641,

%T 4123582463,28975366145,203599740927,1430630760449,10052572086271,

%U 70636158713857,496337248845823,3487600190423041,24506230080798719

%N Number of -5..5 arrays of length n with the sum ahead of each element differing from the sum following that element by 5 or less.

%C Column 5 of A221967.

%H R. H. Hardin, <a href="/A221964/b221964.txt">Table of n, a(n) for n = 1..79</a>

%F Empirical: a(n) = 5*a(n-1) + 18*a(n-2) - 20*a(n-3) - 48*a(n-4) + 16*a(n-5) + 32*a(n-6).

%F Empirical g.f.: 11*x*(1 + 6*x - 12*x^2 - 32*x^3 + 16*x^4 + 32*x^5) / ((1 + x)*(1 - 6*x - 12*x^2 + 32*x^3 + 16*x^4 - 32*x^5)). - _Colin Barker_, Aug 11 2018

%e Some solutions for n=6:

%e ..1....1....1....0...-4....1....2...-4....2....2....1...-5....0....2....2....2

%e .-3...-4...-1....1....2...-5....2....4....0....0....2....4...-2...-2...-2...-3

%e ..0....3...-3....0....5....4...-4...-2...-2...-2...-2....1....3....2...-1...-2

%e ..2....5....4....0...-3...-1....1....0....5...-4....3...-2....0....3....0....3

%e .-4...-5....4...-5....4....3...-3....2...-3....3...-4....1....0....0....1...-1

%e ..2....1...-3....2...-5...-3....3...-4....3....0....5...-3...-3....1...-2....2

%Y Cf. A221967.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 01 2013