A275395 Number of n X 2 0..2 arrays with no element equal to any value at offset (-2,-1) (-2,0) or (-1,1) and new values introduced in order 0..2.

2, 9, 16, 31, 63, 129, 260, 534, 1083, 2210, 4496, 9157, 18653, 37980, 77372, 157551, 320905, 653525, 1331010, 2710764, 5520787, 11243865, 22899407, 46637722, 94983335, 193445757, 393976458, 802382692, 1634153628, 3328158969, 6778215744

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + a(n-2) - 3*a(n-3) + a(n-4) + 4*a(n-5) - 3*a(n-6) + a(n-7) - 2*a(n-8) + a(n-9) for n>10.

Empirical g.f.: x*(2 + 5*x - 4*x^2 - 4*x^3 + 10*x^4 + 3*x^5 - 14*x^6 + 4*x^7 - 2*x^8 + 2*x^9) / (1 - 2*x - x^2 + 3*x^3 - x^4 - 4*x^5 + 3*x^6 - x^7 + 2*x^8 - x^9). - Colin Barker, Feb 04 2019

Example

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

Crossrefs

Column 2 of A275401.

Sequence in context: A101420 A275498 A248434 * A213389 A304907 A237282

Adjacent sequences: A275392 A275393 A275394 * A275396 A275397 A275398

Keyword

nonn

Author

R. H. Hardin, Jul 26 2016

Status

approved