A221964 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.

11, 121, 671, 4961, 34111, 241153, 1690623, 11888129, 83512319, 586864641, 4123582463, 28975366145, 203599740927, 1430630760449, 10052572086271, 70636158713857, 496337248845823, 3487600190423041, 24506230080798719

Offset

1,1

Comments

Column 5 of A221967.

Links

R. H. Hardin, Table of n, a(n) for n = 1..79

Formula

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).

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

Example

Some solutions for n=6:
..1....1....1....0...-4....1....2...-4....2....2....1...-5....0....2....2....2
.-3...-4...-1....1....2...-5....2....4....0....0....2....4...-2...-2...-2...-3
..0....3...-3....0....5....4...-4...-2...-2...-2...-2....1....3....2...-1...-2
..2....5....4....0...-3...-1....1....0....5...-4....3...-2....0....3....0....3
.-4...-5....4...-5....4....3...-3....2...-3....3...-4....1....0....0....1...-1
..2....1...-3....2...-5...-3....3...-4....3....0....5...-3...-3....1...-2....2

Crossrefs

Cf. A221967.

Sequence in context: A338784 A223392 A262468 * A223640 A223633 A223616

Adjacent sequences: A221961 A221962 A221963 * A221965 A221966 A221967

Keyword

nonn

Author

R. H. Hardin, Feb 01 2013

Status

approved