A248490 Number of length 1+5 0..n arrays with some three disjoint pairs in each consecutive six terms having the same sum.

22, 183, 724, 2125, 4986, 10147, 18568, 31449, 50110, 76111, 111132, 157093, 216034, 290235, 382096, 494257, 629478, 790759, 981220, 1204221, 1463242, 1762003, 2104344, 2494345, 2936206, 3434367, 3993388, 4618069, 5313330, 6084331, 6936352

Offset

1,1

Links

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

Formula

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

Empirical for n mod 2 = 0: a(n) = (15/2)*n^4 + 10*n^2 + 11*n + 1.

Empirical for n mod 2 = 1: a(n) = (15/2)*n^4 + 10*n^2 + 11*n - (13/2).

Empirical g.f.: x*(22 + 95*x + 102*x^2 + 144*x^3 - 4*x^4 + x^5) / ((1 - x)^5*(1 + x)). - Colin Barker, Nov 08 2018

Example

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

Crossrefs

Row 1 of A248489.

Sequence in context: A197496 A107969 A248489 * A191012 A248491 A248492

Adjacent sequences: A248487 A248488 A248489 * A248491 A248492 A248493

Keyword

nonn

Author

R. H. Hardin, Oct 07 2014

Status

approved