A232337 Number of 3 X n 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally, with no adjacent elements equal.

1, 16, 74, 154, 628, 1470, 5530, 13906, 49150, 130108, 439834, 1208138, 3956136, 11159566, 35718398, 102702256, 323381538, 942724706, 2933702600, 8637532046, 26653534886, 79035941608, 242412919890, 722524675274, 2206433888880

Offset

1,2

Links

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

Formula

Empirical: a(n) = a(n-1) + 7*a(n-2) - 3*a(n-3) + 3*a(n-4) - 7*a(n-5) + 2*a(n-6) - 2*a(n-7) + 2*a(n-8) for n>12.

Empirical g.f.: x*(1 + 15*x + 51*x^2 - 29*x^3 + x^4 - 55*x^5 + 14*x^6 - 4*x^7 + 20*x^8 - 2*x^10 - 2*x^11) / (1 - x - 7*x^2 + 3*x^3 - 3*x^4 + 7*x^5 - 2*x^6 + 2*x^7 - 2*x^8). - Colin Barker, Oct 05 2018

Example

Some solutions for n=7.
..0..1..2..1..0..1..0....1..2..1..2..1..2..1....0..1..2..1..2..1..0
..0..1..2..1..2..1..2....1..2..1..0..1..2..1....0..1..2..1..2..1..2
..0..1..0..1..0..1..2....1..2..1..0..1..0..2....0..1..2..1..0..1..2

Crossrefs

Row 3 of A232335.

Sequence in context: A299679 A300311 A058333 * A124894 A126403 A197873

Adjacent sequences: A232334 A232335 A232336 * A232338 A232339 A232340

Keyword

nonn

Author

R. H. Hardin, Nov 22 2013

Status

approved