A222891 Number of n X 2 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.

2, 7, 34, 389, 7145, 179465, 5426201, 180390761, 6268113977, 222151991177, 7942488470873, 285058950003113, 10248273625735289, 368717006467136969, 13270285321513993625, 477673900318354951145, 17195359005212203140281

Offset

1,1

Comments

Column 2 of A222894.

Links

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

Formula

Empirical: a(n) = 66*a(n-1) - 1353*a(n-2) + 10648*a(n-3) - 30096*a(n-4) + 20736*a(n-5) for n>7.

Empirical g.f.: x*(2 - 125*x + 2278*x^2 - 13680*x^3 + 13129*x^4 + 41380*x^5 - 15264*x^6) / ((1 - x)*(1 - 4*x)*(1 - 9*x)*(1 - 16*x)*(1 - 36*x)). - Colin Barker, Aug 16 2018

Example

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

Crossrefs

Cf. A222894.

Sequence in context: A136310 A222868 A222777 * A342411 A231580 A182408

Adjacent sequences: A222888 A222889 A222890 * A222892 A222893 A222894

Keyword

nonn

Author

R. H. Hardin, Mar 08 2013

Status

approved