A230529 Number of n X 2 0..6 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 7, and upper left element zero.

0, 0, 0, 0, 0, 0, 2, 8, 32, 120, 432, 1512, 5182, 17500, 58432, 193360, 635296, 2075248, 6746882, 21848960, 70523816, 227010760, 729035536, 2336660440, 7476771198, 23889669636, 76238228904, 243039699792, 774082314048, 2463524146272

Offset

1,7

Comments

Column 2 of A230533.

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - 4*a(n-3) - 8*a(n-4) - 12*a(n-5) - 17*a(n-6) - 10*a(n-7).

Empirical g.f.: 2*x^7 / (1 - 4*x + 4*x^3 + 8*x^4 + 12*x^5 + 17*x^6 + 10*x^7). - Colin Barker, Mar 17 2018

Example

All solutions for n=7:
..0..6....0..1
..1..5....6..2
..2..4....5..3
..3..3....4..4
..4..2....3..5
..5..1....2..6
..6..0....1..0

Crossrefs

Cf. A230533.

Sequence in context: A230509 A099752 A230393 * A282879 A217665 A337863

Adjacent sequences: A230526 A230527 A230528 * A230530 A230531 A230532

Keyword

nonn

Author

R. H. Hardin, Oct 22 2013

Status

approved